BEGIN:VCALENDAR METHOD:PUBLISH PRODID:Microsoft Exchange Server 2010 VERSION:2.0 X-WR-CALNAME:The ZX Seminar BEGIN:VTIMEZONE TZID:W. Europe Standard Time BEGIN:STANDARD DTSTART:16010101T030000 TZOFFSETFROM:+0200 TZOFFSETTO:+0100 RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10 END:STANDARD BEGIN:DAYLIGHT DTSTART:16010101T020000 TZOFFSETFROM:+0100 TZOFFSETTO:+0200 RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3 END:DAYLIGHT END:VTIMEZONE BEGIN:VEVENT DESCRIPTION:Abstract: I will give an overview of our new\, open-access text book "Picturing Quantum Software: An Introduction to the ZX-Calculus and Q uantum Compilation" (https://github.com/zxcalc/book)\, and highlight the m ajor topics it covers\, including applications of ZX to circuit optimisati on\, classical simulation\, and quantum error correction.\n\nOpen-source t extbook: https://github.com/zxcalc/book\n\nSpeaker: Aleks Kissinger\n\nZoom link: https://uva-live.zoom.us/j/6265641400 5\n\nJoint-work with: John van de Wetering\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E008000000001070C844FB27DC01000000000000000 010000000FA13AC63FE8C3840B90CB106751AD979 SUMMARY:Picturing Quantum Software DTSTART;TZID=W. Europe Standard Time:20250929T150000 DTEND;TZID=W. Europe Standard Time:20250929T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:2 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:2 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Christine Li\nZoom link: https://uva-live.zoom.us/j/62 656414005\nAbstract: It is a truth universally acknowledged that it is imp ossible to deterministically do a two-qubit binary AND gate. In this talk\ , we first show how to do a two-qutrit Clifford+T gate which performs bina ry AND on the qubit subspace of the qutrit. We thereafter construct a nove l [[6\,2\,2]] qutrit error correcting code which can fault-tolerantly do t his binary AND gate. The key insight is to interpret a symmetric T-depth o ne circuit as a distance 1 code\, then add stabilizers to increase the cod e distance. By a different choice of logical operators\, this transversal gate can also be the logical |0⟩-controlled X gate\, which may be of ind ependent interest as it generalizes the Toffoli gate to qutrits.\nJoint-Wo rk With: Lia Yeh\n\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E00800000000979504F70E32DC01000000000000000 01000000014A5DE2565C6C64AAC516A451BAE7B1F SUMMARY:A Novel Qutrit Code with a Transversal Binary AND Gate DTSTART;TZID=W. Europe Standard Time:20251006T150000 DTEND;TZID=W. Europe Standard Time:20251006T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Charles (ChunJun) Cao\narXiv: https://arxiv.org/pdf/2507.13496\nZo om link: https://uva-live.zoom.us/j/62656414005\nAbstract: It is generally unclear whether smaller codes can be “concatenated” to systematically create quantum LDPC codes or their sparse subsystem code cousins where th e degree of the Tanner graph remains bounded while increasing the code dis tance. In this work\, we use a slight generalization of concatenation call ed conjoining introduced by the quantum lego formalism. We show that by co njoining only quantum repetition codes\, one can construct quantum LDPC co des. More generally\, we provide an efficient iterative algorithm for cons tructing sparse subsystem codes with a distance guarantee that asymptotica lly saturates kd^2=O(n) in the worst case. Furthermore\, we show that the conjoining of even just two-qubit quantum bit-flip and phase-flip repetiti on codes is quite powerful as they can create any CSS code. Therefore\, mo re creative combinations of these basic code blocks will be sufficient for generating good quantum codes\, including good quantum LDPC codes.\nJoint -Work With: Brad Lackey\n UID:040000008200E00074C5B7101A82E0080000000091CE0D66302ADC01000000000000000 0100000009F481FE85BEA204AAC0F7702F7EE3091 SUMMARY:Growing Sparse Quantum Codes from a Seed DTSTART;TZID=W. Europe Standard Time:20251013T150000 DTEND;TZID=W. Europe Standard Time:20251013T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Byungmin Kang\narXiv: https://arxiv.org/pdf/2505.06336\nZoom link: https://uva-live.zoom.us/j/62656414005\nAbstract: Simulating generic quan tum states and dynamics is practically intractable using classical compute rs. However\, certain special classes—namely Clifford and matchgate circ uits—permit efficient computation. They provide invaluable tools for stu dying many-body physics\, quantum chemistry\, and quantum computation. Whi le both play foundational roles across multiple disciplines\, the origins of their tractability seem disparate\, and their relationship remain uncle ar. A deeper understanding of such tractable classes could expand their sc ope and enable a wide range of new applications. In this work\, we make pr ogress toward the unified understanding of the Clifford and matchgate—th ese two classes are\, in fact\, distinct special cases of a single underly ing structure. Specifically\, we introduce the 2D Quon language\, which co mbines Majorana worldlines with their underlying spacetime topology to dia grammatically represent quantum processes and tensor networks. In full gen erality\, the 2D Quon language is universal—capable of representing arbi trary quantum states\, dynamics\, or tensor networks—yet they become esp ecially powerful in describing Clifford and matchgate classes. Each class can be efficiently characterized in a visually recognizable manner using t he Quon framework. This capability naturally gives rise to several familie s of efficiently computable tensor networks introduced in this work: punct ured matchgates\, hybrid Clifford-matchgate-MPS\, and ansatze generated fr om factories of tractable networks. All of these exhibit high non-Clifford ness\, high non-matchgateness\, and large bipartite entanglement entropy. We discuss a range of applications of our approach\, from recovering well- known results such as the Kramers-Wannier duality and the star-triangle re lation of the Ising model\, to enabling variational optimization with nove l ansatz states.\nJoint-Work With: Chen Zhao\, Zhengwei Liu\, Xun Gao\, an d Soonwon Choi\n\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E00800000000F12B5F078529DC01000000000000000 01000000057DF4BE5CA84AA49BA953E7CB43E38DE SUMMARY:2D Quon Language: Unifying Framework for Cliffords\, Matchgates\, a nd Beyond DTSTART;TZID=W. Europe Standard Time:20251020T150000 DTEND;TZID=W. Europe Standard Time:20251020T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Austin Fowler\n\nZoom link: https://uva-live.zoom.us/j /82515320751\nAbstract: Executing a large-scale fault-tolerant quantum alg orithm requires not only hardware that currently doesn't exist\, but also software that currently doesn't exist. It is extremely challenging to comp ile a quantum algorithm even to a monolithic 2D square array of qubits wit h nearest neighbor couplings only. The tqec project is initially focused o n building a full stack compiler for such an architecture. This will provi de a baseline for future work with more complex architectures.\n\nIn this talk\, we will review our progress towards compiling algorithms to a 2D ar ray\, working through the surface code\, lattice surgery\, and the deep co nnection to ZX graphs.\n\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E00800000000407A0017E423DC01000000000000000 0100000008D4D29A11D92FF49B8E429003A176A9F SUMMARY: TQEC: ZX Graphs and Lattice Surgery DTSTART;TZID=W. Europe Standard Time:20251027T170000 DTEND;TZID=W. Europe Standard Time:20251027T183000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:2 LOCATION:https://uva-live.zoom.us/j/82515320751 X-MICROSOFT-CDO-APPT-SEQUENCE:2 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Mateusz Kupper\n\narXiv: https://arxiv.org/pdf/2508.14672\nZoom li nk: https://uva-live.zoom.us/j/62656414005\nAbstract: Surface codes are a popular choice for implementing fault-tolerant quantum computing. Two-qubi t gates may be realised in these codes using only nearest-neighbour intera ctions\, either by lattice surgery [27] or by braiding defects around each other [43]. The effect of lattice surgery operations may be simply descri bed [3] using the ZX-calculus: a graphical language that has proven effect ive for program design and optimisation (see e.g. [23]). In this work\, we formalise a similar description via the ZX-calculus of defect braiding\, as it is conventionally described. We define a graphical calculus KNOT\, d enoting the logical effects (in the absence of byproduct operations) of de fect braiding in surface codes: we show how these effects may be described via a fragment of ZX-calculus which we call the (0\, π)-fragment. We the n use a ‘doubling’ construction to define a subtheory of KNOT\, more s pecialised to standard encoding techniques in the defect braiding literatu re. Within this subtheory\, we encompass standard braiding techniques by f amilies of ‘ribbon-like’ and ‘tangle-like’ diagrams\, each with se mantics distinct from KNOT\, in terms of the (0\, π)-fragment of ZX diagr ams (again in the absence of byproducts). These subtheories may be used in teroperably\, and are each sound and complete for the (0\, π)-fragment of ZX diagrams. This provides a starting point to use the formal diagrammati cs to analyse the operational effects of defect braiding procedures.\n[3] de Beaudrap\, N.\, & Horsman\, D. (2017). The ZX calculus is a language fo r surface code lattice surgery. arXiv preprint arXiv:1704.08670.\n[23] Gid ney\, C.\, & Fowler\, A. G. (2018). Efficient magic state factories with a catalyzed| CCZ> to 2| T> transformation. arXiv preprint arXiv:1812.01238. \n[27] Horsman\, D.\, Fowler\, A. G.\, Devitt\, S.\, & Van Meter\, R. (201 2). Surface code quantum computing by lattice surgery. New Journal of Phys ics\, 14(12)\, 123011.\n[43] Raussendorf\, R.\, Harrington\, J.\, & Goyal\ , K. (2007). Topological fault-tolerance in cluster state quantum computat ion. New Journal of Physics\, 9(6)\, 199.\nJoint-Work With: Dominic Horsma n\, Chris Heunen\, and Niel de Beaudrap\n UID:040000008200E00074C5B7101A82E008000000005EE9DBE08729DC01000000000000000 01000000080BA458EDAF0F4419E227AA1CF9DD63C SUMMARY:String Diagrams for Defect-Based Surface Code Computing DTSTART;TZID=W. Europe Standard Time:20251103T150000 DTEND;TZID=W. Europe Standard Time:20251103T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Andreas Bauer\narXiv: https://arxiv.org/pdf/2505.05175\nZoom link: https://uva-live.zoom.us/j/62656414005\nAbstract: We introduce a family o f scalable planar fault-tolerant circuits that implement logical non-Cliff ord operations on a 2D color code\, such as a logical T gate or a logical non-Pauli measurement that prepares a magic |T⟩ state. The circuits are relatively simple\, consisting only of physical T gates\, CX gates\, and f ew-qubit measurements. They can be implemented with an array of qubits on a 2D chip with nearest-neighbor couplings\, and no wire crossings. The con struction is based on a spacetime path integral representation of a non-Ab elian 2+1D topological phase\, which is related to the 3D color code. We t urn the path integral into a circuit by expressing it as a spacetime ZX te nsor network\, and then traversing it in some chosen time direction. We de scribe in detail how fault tolerance is achieved using a “just-in-time ” decoding strategy\, for which we repurpose and extend state-of-the-art color-code matching decoders.\nJoint-Work With: Julio C. Magdalena de la Fuente\n\n________________________________________________________________ ________________\nMicrosoft Teams Need help?\nJoin the meeting now\nMeeting ID: 3 35 436 440 162 3\nPasscode: PA6ed9mx\n________________________________\nFo r organizers: Meeting options\n___________________ _____________________________________________________________\n UID:040000008200E00074C5B7101A82E00800000000F8E31DAE8C29DC01000000000000000 0100000007CB35D2A73EFBC409B5745AC1676C442 SUMMARY:Planar Fault-Tolerant Circuits for Non-Clifford Gates on the 2D Col or Code DTSTART;TZID=W. Europe Standard Time:20251110T150000 DTEND;TZID=W. Europe Standard Time:20251110T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Alejandro Villoria\narXiv: https://arxiv.org/pdf/2507.20694\nZoom link: https://uva-live.zoom.us/j/62656414005\nAbstract: Compiling quantum circuits to account for hardware restrictions is an essential part of the quantum computing stack. Circuit compilation allows us to adapt algorithm descriptions into a sequence of operations supported by real quantum hardw are\, and has the potential to significantly improve their performance whe n optimization techniques are added to the process. One such optimization technique is reducing the number of quantum gates that are needed to execu te a circuit. For instance\, methods for reducing the number of non-Cliffo rd gates or CNOT gates from a circuit is an extensive research area that h as gathered significant interest over the years. For certain hardware plat forms such as ion trap quantum computers\, we can leverage some of their s pecial properties to further reduce the cost of executing a quantum circui t in them. In this work we use global interactions\, such as the Global M ølmer-Sørensen gate present in ion trap hardware\, to optimize and synth esize quantum circuits. We design and implement an algorithm that is able to compile an arbitrary quantum circuit into another circuit that uses glo bal gates as the entangling operation\, while optimizing the number of glo bal interactions needed. The algorithm is based on the ZX-calculus and use s a specialized circuit extraction routine that groups entangling gates in to Global Mølmer-Sørensen gates. We benchmark the algorithm in a variety of circuits\, and show how it improves their performance under state-of-t heart hardware considerations in comparison to a naive algorithm and the Q iskit optimizer.\nJoint-Work With: Henning Basold and Alfons Laarman\n UID:040000008200E00074C5B7101A82E00800000000D2BA01FC8A29DC01000000000000000 01000000081DB8AF6DCA0024CBBFE49AFAAA016A5 SUMMARY:Optimization and Synthesis of Quantum Circuits with Global Gates DTSTART;TZID=W. Europe Standard Time:20251117T150000 DTEND;TZID=W. Europe Standard Time:20251117T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Collin (Yuanjie) Ren\narXiv: https://arxiv.org/pdf/250 8.03976\nZoom link: https://uva-live.zoom.us/j/62656414005\nAbstract: We i ntroduce a graphical calculus\, consisting of a set of fermionic tensors w ith tensor-network equations\, which can be used to perform various comput ations in fermionic many-body physics purely diagrammatically. The indices of our tensors primarily correspond to fermionic modes\, but also include qubits and fixed odd-parity states. Our graphical calculus extends the ZX calculus for systems involving qubits. We apply the calculus in order to represent various objects\, operations\, and computations in physics\, inc luding fermionic Gaussian states\, the partial trace of Majorana modes\, p urification protocols\, fermionization and bosonization maps\, and the con struction of fermionic codes.\nJoint-Work With: Kaifeng Bu and Andreas Bau er\n\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E008000000004F560B0F8629DC01000000000000000 0100000002403D9CD70D98C4B85A3E7E5771D2122 SUMMARY:Graphical Calculus for Fermionic Tensors DTSTART;TZID=W. Europe Standard Time:20251124T150000 DTEND;TZID=W. Europe Standard Time:20251124T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Ewan Murphy\n\nZoom link: https://uva-live.zoom.us/j/6 2656414005\n\nAbstract: Clifford circuits are a subset of all possible qua ntum circuits that are known to be simulable on a classical computer in po lynomial time. These circuits form the backbone of most modern quantum err or-correction protocols. To understand the performance of these protocols\ , we perform numerical simulations of such circuits under specific noise m odels.\n\nThe software used by almost all researchers in quantum error cor rection to perform these simulations is called Stim\, a Python library dev eloped by Craig Gidney\, a researcher at Google Quantum AI. In this tutori al I will provide an introduction to Stim\, discussing some of its main fe atures and how to use them. I will show you how to simulate an arbitrary C lifford circuit\, as well as how to find the threshold of an error-correct ing code. A brief understanding of quantum error correction will be helpfu l\, but I will try to explain any new concepts as they appear. At the end\ , I will provide references for useful resources for anyone who wants to l earn more about how to use this tool in research.\n\n\nSent from Outlook f or Mac\n UID:040000008200E00074C5B7101A82E00800000000F919FA6C8529DC01000000000000000 0100000005CD5AA05A1B7E647887D9F2749622221 SUMMARY:Stim 101: Quantum Stabilizer Simulation Made Simple DTSTART;TZID=W. Europe Standard Time:20251201T150000 DTEND;TZID=W. Europe Standard Time:20251201T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:3 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:3 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Daniel Litinski\n\narXiv: https://arxiv.org/pdf/2506.13619\nZoom l ink: https://uva-live.zoom.us/j/62656414005\nAbstract: We introduce a cons truction for protocols for fault-tolerant quantum computing based on code concatenation and transversal gates. These protocols can be interpreted as families of quantum circuits of low-weight stabilizer measurements withou t strict locality constraints\, effectively implementing concatenated code s. However\, we primarily study these protocols in the context of photonic fusion-based quantum computing (FBQC)\, where they yield families of fusi on networks with constant-sized resource states. Their high erasure thresh olds relative to their resource-state cost establish them as promising can didates to replace surface codes in the context of FBQC. Examples include protocol families using 8-\, 10- and 12-qubit resource states\, with erasu re thresholds of 13.8%\, 19.1% and 11.5%\, and footprint-per-logical-qubit scaling as O(d)\, O(d^1.46) and O(d^0.58)\, respectively\, where d is the code distance. We also present techniques for performing logical operatio ns\, decoding\, and implementing the protocols in photonic hardware. Altho ugh we focus on photonic FBQC\, these ideas may also be of interest in oth er settings.\n\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E0080000000089F8072F2B2EDC01000000000000000 0100000003D0DEA7B0AA3014A843115B125493B71 SUMMARY:Blocklet Concatenation: Low-Overhead Fault-Tolerant Protocols for F usion-Based Quantum Computation. DTSTART;TZID=W. Europe Standard Time:20251208T150000 DTEND;TZID=W. Europe Standard Time:20251208T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Sergi Mas-Mendoza\narXiv: https://arxiv.org/pdf/2509.1 2355\nZoom link: https://uva-live.zoom.us/j/62656414005\nAbstract: Establi shing a universal diagnostic of topological order remains an open theoreti cal challenge. In particular\, diagnosing long-range entanglement through the entropic area law suffers from spurious contributions\, failing to una mbiguously identify topological order. Here we devise a protocol based on the ZX calculus\, a graphical tensor network\, to determine the topologica l order of a state circumventing entropy calculations. The protocol takes as input real-space bipartitions of a state and returns a ZX contour diagr am\, D∂A\, displaying long-range graph connectivity only for long-range entangled states. We validate the protocol by showing that the contour dia grams of the toric and color codes are equivalent except for the number of non-local nodes\, which differentiates their topological order. The numbe r of these nodes is robust to the choice of the boundary and ground-state superposition\, and they are absent for trivial states\, even those with s purious entropy contributions. Our results single out ZX calculus as a too l to detect topological long-range entanglement by leveraging the advantag es of diagrammatic reasoning against entropic diagnostics.\nJoint-Work Wit h: Richard D. P. East\, Michele Filippone\, and Adolfo G. Grushin\n\nSent from Outlook for Mac\n UID:040000008200E00074C5B7101A82E00800000000CD56E345332DDC01000000000000000 0100000005CA0AF1DD5C1D54C86D07C6B56FBF319 SUMMARY:A Graphical Diagnostic of Topological Order Using ZX Calculus DTSTART;TZID=W. Europe Standard Time:20251215T150000 DTEND;TZID=W. Europe Standard Time:20251215T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:1 LOCATION:https://uva-live.zoom.us/j/62656414005 X-MICROSOFT-CDO-APPT-SEQUENCE:1 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Tobias Fischbach (University of Luxembourg)\narXiv: https://arxiv.org/pdf/2509.2066 3\nZoom link: https://uva-live.zoom.us/j/65093307759\nAbstract: Quantum co mputing promises significant speed-ups for certain algorithms but the prac tical use of current noisy intermediate-scale quantum (NISQ) era computers remains limited by resources constraints (e.g.\, noise\, qubits\, gates\, and circuit depth). Quantum circuit optimization is a key mitigation stra tegy. In this context\, ZX-calculus has emerged as an alternative framewor k that allows for semantics-preserving quantum circuit optimization.\n\nWe review ZX-based optimization of quantum circuits\, categorizing them by o ptimization techniques\, target metrics and intended quantum computing arc hitecture. In addition\, we outline critical challenges and future researc h directions\, such as multi-objective optimization\, scalable algorithms\ , and enhanced circuit extraction methods. This survey is valuable for res earchers in both combinatorial optimization and quantum computing. For res earchers in combinatorial optimization\, we provide the background to unde rstand a new challenging combinatorial problem: ZX-based quantum circuit o ptimization. For researchers in quantum computing\, we classify and explai n existing circuit optimization techniques.\n\n\nJoint-Work With: Pierre T albot and Pascal Bouvry\n UID:040000008200E00074C5B7101A82E00800000000FB32E3FA1E6DDC01000000000000000 010000000FCC7087B8F3DDE43BA82B4432822496D SUMMARY:A Review on Quantum Circuit Optimization using ZX-Calculus DTSTART;TZID=W. Europe Standard Time:20260202T150000 DTEND;TZID=W. Europe Standard Time:20260202T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:1 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:1 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Maike Ostmann (ORCA Computing)\n\narXiv: https://arxiv.org/pdf/251 0.06890\nZoom link: https://uva-live.zoom.us/j/65093307759\nAbstract: We p ropose a novel architecture for fault-tolerant quantum computing that inco rporates strong single-photon nonlinearities into a photonic GHZ-measureme nt-based architecture. The nonlinearities substantially reduce resource ov erheads compared to conventional linear-optics-based architectures\, which require significant redundancy to accommodate probabilistic photon genera tion and probabilistic entangling operations. By removing linear-optical f ailure modes\, our nonlinear architecture can also tolerate much higher op tical losses than linear approaches\, with a baseline loss tolerance of ∼12% using a 32-photon resource state and a foliated surface code. Our r esults show how introducing a nonlinear primitive enables dramatic improve ments in practical implementations of fault-tolerant quantum computing.\n\ nJoint-Work With: Joshua Nunn and Alex E. Jones\n UID:040000008200E00074C5B7101A82E00800000000171056C38E6EDC01000000000000000 010000000B1F8A34BD533684296F17118F90E0C39 SUMMARY:Nonlinear Photonic Architecture for Fault-Tolerant Quantum Computin g DTSTART;TZID=W. Europe Standard Time:20260209T150000 DTEND;TZID=W. Europe Standard Time:20260209T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Maximilian Rüsch (Quantinuum)\narXiv: https://arxiv.o rg/pdf/2510.08477\nZoom link: https://uva-live.zoom.us/j/65093307759\nAbst ract: Two circuits are considered to be equivalent under noise if the effe ct of faults on one circuit is no worse than the effect of faults on the o ther circuit. We call this relationship fault equivalence. Fault equivalen ce offers a way to transform circuits while provably preserving their faul t-tolerant properties\, enabling a framework for faulttolerant circuit syn thesis and optimisation that is correct by construction. The ZX calculus\, a set of graphical rewrite rules for quantum computations\, provides a us eful tool for manipulating circuits while preserving fault equivalence. Fo r this\, the usual set of ZX rewrites has to be restricted to not only pre serve the underlying linear map represented by the diagram but also fault equivalence.\n\nIn this work\, we provide a set of ZX rewrites that are so und and complete for fault equivalence of Clifford ZX diagrams. This means that any equivalence that can be derived using the proposed rules is cert ain to be correct\, and any correct equivalence can be derived using only these rules. For this\, we utilise diagrammatic constructions called fault gadgets to reason about arbitrary\, possibly correlated Pauli faults in Z X diagrams. Fault gadgets allow us to separate the diagram into a fault-fr ee part\, which captures the noise-free behaviour of a diagram\, and a noi sy part that enumerates the effects of all possible faults. Using this\, w e provide a unique normal form for ZX diagrams under noise and show that a ny diagram can be brought into this normal form using our proposed rule se t.\n\n\nJoint-Work With: Benjamin Rodatz and Aleks Kissinger\n UID:040000008200E00074C5B7101A82E00800000000973AB9EC496CDC01000000000000000 0100000005791F8694D653944880D926594196265 SUMMARY:Completeness for Fault Equivalence of Clifford ZX Diagrams DTSTART;TZID=W. Europe Standard Time:20260216T150000 DTEND;TZID=W. Europe Standard Time:20260216T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Vivien Vandaele (Quantinuum)\nPhD Thesis: https://inspirehep.net/f iles/1b9b518d03054c5810e04caaa89b6626\nZoom link: https://uva-live.zoom.us /j/65093307759\nAbstract: This talk presents a series of results forming a logical-level optimization stack for fault-tolerant quantum computing. We introduce a method for minimizing the number of Hadamard gates\, which is relevant to design efficient non-Clifford gate count optimizers. We also present algorithms for optimizing the T-count and the number of qubits in quantum circuits. We show how these procedures relate to one another and c ombine into a unified optimizer for fault-tolerant quantum computing. The ZX-calculus is used throughout\, either to exemplify these procedures intu itively or to formulate and solve the optimization problems.\n UID:040000008200E00074C5B7101A82E0080000000039097820C56ADC01000000000000000 0100000002FE7962A9B9CBC4596954301546527D5 SUMMARY:Optimization of Fault-Tolerant Quantum Computing by the ZX-Calculus DTSTART;TZID=W. Europe Standard Time:20260223T150000 DTEND;TZID=W. Europe Standard Time:20260223T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:1 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:1 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Rafael Haenel and Chen Zhao\nGitHub: https ://github.com/QuEraComputing/tsim\nZoom link: https://uva-live.zoom.us/j/6 5093307759\nAbstract: We present tsim\, a high-throughput universal quantu m circuit simulator designed for quantum error correction with native GPU support. In tsim\, quantum circuits are represented as ZX diagrams\, where Pauli channels are modeled as parametrized vertices. Diagrams are compile d for vectorized sampling as described in Sutcliffe et al. 2025. And tsim fully supports the stim format and extends it with T and arbitrary rotatio n instructions. For pure Clifford and low-magic circuits\, tsim throughput can match or even exceed the sampling performance of stim.\n UID:040000008200E00074C5B7101A82E008000000004F4FC294E5A1DC01000000000000000 0100000007D557F7702A2BA4B8256A464ECA4FA0C SUMMARY:Fast Simulation of Universal Quantum Circuits under Pauli Noise via ZX Stabilizer Rank Decomposition DTSTART;TZID=W. Europe Standard Time:20260302T150000 DTEND;TZID=W. Europe Standard Time:20260302T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:1 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:1 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Yuchen Pang\narXiv: https://arxiv.org/pdf/2511.06012\nZoom link: h ttps://uva-live.zoom.us/j/65093307759\nAbstract: Quantum circuits are cons idered more powerful than classical circuits and require exponential resou rces to simulate classically. Clifford circuits are a special class of qua ntum circuits that can be simulated in polynomial time but still show impo rtant quantum effects such as entanglement. In this work\, we present an a lgorithm that simulates Clifford circuits by performing Gaussian eliminati on on a modified adjacency matrix derived from the circuit structure. Our work builds on an ZX-calculus tensor network representation of Clifford ci rcuits that reduces to quantum graph states. We give a concise formula of amplitudes of graph states based on the LDL decomposition of matrices over GF(2)\, and use it to get efficient algorithms for strong and weak simula tion of Clifford circuits using tree-decomposition-based fast LDL algorith m. The complexity of our algorithm matches the state of art for weak graph state simulation and improves the state of art for strong graph state sim ulation by taking advantage of Strassen-like fast matrix multiplication. O ur algorithm is also efficient when computing many amplitudes or samples o f a Clifford circuit. Further\, our amplitudes formula provides a new char acterization of locally Clifford equivalent graph states as well as an eff icient protocol to learn graph states with low-rank adjacency matrices.\nJ oint-Work With: Edgar Solomonik\n\n UID:040000008200E00074C5B7101A82E0080000000037BFC2EABA6ADC01000000000000000 010000000D9D76B85BD0BDF4E85F32079D560F090 SUMMARY:Simulating Clifford Circuits with Gaussian Elimination DTSTART;TZID=W. Europe Standard Time:20260316T150000 DTEND;TZID=W. Europe Standard Time:20260316T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:1 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:1 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Quanlong Wang\narXiv: https://arxiv.org/pdf/2511.06012\nZoom link: https://uva-live.zoom.us/j/65093307759\nAbstract: We introduce the Spin-Z X calculus as an elevation of Penrose’s diagrams and associated binor ca lculus to the level of a formal diagrammatic language. The power of doing so is illustrated by the variety of scientific areas we apply it to: permu tational quantum computing\, quantum machine learning\, condensed matter p hysics\, and quantum gravity. Respectively\, we analyse permutational comp uting transition amplitudes\, evaluate barren plateaus for SU(2) symmetric ansatze\, study properties of AKLT states\, and derive the minimum quanti sed volume in loop quantum gravity.\n\nOur starting point is the mixed-dim ensional ZX calculus\, a purely diagrammatic language that has been proven to be complete for finite-dimensional Hilbert spaces. That is\, any equat ion that can be derived in the Hilbert space formalism\, can also be deriv ed in the mixed-dimensional ZX calculus. We embed the Spin-ZX calculus ins ide the mixeddimensional ZX calculus\, rendering it a quantum information flavoured diagrammatic language for the quantum theory of angular momentum \, i.e. SU(2) representation theory. We diagrammatically derive the fundam ental spin coupling objects — such as Clebsch-Gordan coefficients\, symm etrising mappings between qubits and spin spaces\, and spin Hamiltonians — under this embedding.\n\nOur results establish the Spin-ZX calculus as a powerful tool for representing and computing with SU(2) systems graphic ally\, offering new insights into foundational relationships and paving th e way for new diagrammatic algorithms for theoretical physics.\n\n\nJoint- Work With: Richard D. P. East\, Razin A. Shaikh\, Lia Yeh\, Boldizsár Po ór\, and Bob Coecke\n UID:040000008200E00074C5B7101A82E00800000000711840FAB96ADC01000000000000000 010000000B903B23033109B45AE4F49A70214691A SUMMARY:Beyond Penrose Tensor Diagrams with the ZX Calculus DTSTART;TZID=W. Europe Standard Time:20260323T150000 DTEND;TZID=W. Europe Standard Time:20260323T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Andrey Boris Khesin\narXiv: https://arxiv.org/pdf/2603.05391\nZoo m link: https://uva-live.zoom.us/j/65093307759\nAbstract: The ability to f ault-tolerantly prepare CAT states\, also known as multiqubit GHZ states\, is an important primitive for quantum error correction. It is required fo r Shor-style syndrome extraction\, and can also be used as a subroutine fo r doing fault-tolerant state preparation of CSS codewords. Existing approa ches to fault-tolerant CAT state preparations have been found using comput ationally expensive heuristics involving SAT solving\, reinforcement learn ing\, or exhaustive analysis. In this paper\, we constructively find optim al circuits for CAT states in a more scalable way. In particular\, we deri ve formal lower bounds on the number of CNOT gates required for circuits i mplementing n-qubit CAT states that do not spread errors of weight at most t for 1 ≤ t ≤ 5. We do this by using fault-equivalent rewrites of ZX- diagrams to reduce it to a problem of characterising certain 3-regular sim ple graphs. We then provide families of such optimal graphs for infinitely many values of n and t ≤ 5. By encoding the construction of optimal gra phs as a constraint satisfaction problem we find explicit constructions fo r circuits that match this lower bound on CNOT count for all n ≤ 50 and t ≤ 5 and for nearly all pairs (n\, t) with n ≤ 100 and t ≤ 5 or n ≤ 50 and t ≤ 7\, significantly extending the regimes that were achieva ble by previous methods and improving the resource counts for existing con structions. We additionally show how to trade CNOT count against depth\, a llowing us to construct constant-depth fault-tolerant implementations usin g O(n) ancilla and O(n) CNOT gates.\n\nJoint-work with: Sarah Meng Li\, Bo ldizsár Poór\, Benjamin Rodatz\, John van de Wetering\, and Richie Yeung \n UID:040000008200E00074C5B7101A82E008000000001C9540E382ADDC01000000000000000 01000000065E173E0515B524F9D6133C773C81B23 SUMMARY:SpiderCat: Optimal Fault-Tolerant Cat State Preparation DTSTART;TZID=W. Europe Standard Time:20260330T150000 DTEND;TZID=W. Europe Standard Time:20260330T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Peter-Jan H. S. Derks\narXiv: https://arxiv.org/pdf/2505.07658\nZo om link: https://uva-live.zoom.us/j/65093307759\nAbstract: Dynamical stabi lizer codes may offer a practical route to large-scale quantum computation . Such codes are defined by a schedule of error-detecting measurements\, w hich allows for flexibility in their construction. In this work\, we ask h ow best to optimise the measurement schedule of dynamically condensed colo ur codes in various limits of noise bias. We take a particular focus on th e setting where measurements introduce more noise than unitary and idling operations – a noise model relevant to some hardware proposals. For meas urementbiased noise models\, we improve code performance by strategically repeating measurements within the schedule. For unbiased or Z-biased noise models\, we find repeating measurements offers little improvement – som ewhat contrary to our expectations – and investigate why this is. To per form this analysis\, we generalise a metric called the teraquop footprint to the teraquop volume. This is the product of the number of qubits and nu mber of rounds of measurements required such that the probability of a spa celike or timelike logical error occurring is less than 10−12. In most c ases\, we find differences in performance are primarily due to the number of rounds of measurements required\, rather than the number of qubits – emphasising the importance of using the teraquop volume in the analysis. A dditionally\, our results provide another example of the importance of mak ing use of correlated errors when decoding\, in that using belief matching rather than minimum-weight perfect matching can turn a worst-performing c ode under a given noise model into a best-performing code.\nJoint-Work Wit h: Alex Townsend-Teague\, Jens Eisert\, Markus S. Kesselring\, Oscar Higgo tt\, and Benjamin J. Brown\n UID:040000008200E00074C5B7101A82E008000000005AB770E67B6BDC01000000000000000 010000000AEE53ABA07C9564CA6F3AA9B51D2F9E4 SUMMARY:Dynamical Codes for Hardware with Noisy Readouts DTSTART;TZID=W. Europe Standard Time:20260413T150000 DTEND;TZID=W. Europe Standard Time:20260413T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Thomas Perez (Institut Polytechnique de Paris)\narXiv: https://arxiv.org/pdf/2508.14671\nZoom link: https://uva-live.zoom.us/j/6 5093307759\nAbstract: In the one-way model of measurement-based quantum co mputation (MBQC)\, computation proceeds via single-qubit measurements on a resource state. Flow conditions ensure that the overall computation is de terministic in a suitable sense\, and are required for efficient translati on into quantum circuits. Procedures that rewrite MBQC patterns – e.g. f or optimisation\, or adapting to hardware constraints – thus need to pre serve the existence of flow. Most previous work has focused on rewrites th at reduce the number of qubits in the computation\, or that introduce new Pauli-measured qubits.\n\nHere\, we consider the insertion of planar-measu red qubits into MBQC patterns\, i.e. arbitrary measurements in a plane of the Bloch sphere spanned by a pair of Pauli operators\; such measurements are necessary for universal MBQC. We extend the definition of causal flow\ , previously restricted to XY-measurements only\, to also permit YZ-measur ements and derive the conditions under which a YZ-insertion preserves caus al flow. Then we derive conditions for YZ-insertion into patterns with gfl ow or Pauli flow\, in which case the argument straightforwardly extends to XZ-insertions as well. We also show that the ‘vertex splitting’ or ‘neighbour unfusion’ rule previously used in the literature can be der ived from YZ-insertion and pivoting. This work contributes to understandin g the broad properties of flow-preserving rewriting in MBQC and in the ZX- calculus more broadly\, and it will enable more efficient optimisation\, o bfuscation\, or routing.\nJoint-Work With: Miriam Backens\n\n UID:040000008200E00074C5B7101A82E008000000007ADFC08BEC70DC01000000000000000 010000000C416E4C5EF5EA74C902B371AB02006ED SUMMARY:Inserting Planar-Measured Qubits into MBQC Patterns while Preservin g Flow DTSTART;TZID=W. Europe Standard Time:20260420T150000 DTEND;TZID=W. Europe Standard Time:20260420T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Kwok Ho Wan (PsiQuantum)\narXiv: https://arxiv.org/pdf/2509.08658\nZoom link: https://uva-live.zoom.us/j/6 5093307759\nAbstract: Building upon [arXiv:2509.01224]\, we present a sketch on how to simulate the non-Clifford d =5 magic state cultivation circuits [arXiv:2409.17595] with a sum of ≈8 Clifford ZX-diagrams on average\, at 0.1 % noise. Compared to a magic cat state stabiliser decomposition of all 53 non-Clifford spiders (6\,377\,292 terms required)\, this is more than 7×1 0^5 times reduction in the number of terms. Our stabiliser decomposition h as the advantage of representing the final non-Clifford state (in light of circuit errors) as a sum of Clifford ZX-diagrams. This will be useful in simulating the escape stage of magic state cultivation\, where one needs t o port the resultant state of cultivation into a larger Clifford circuit w ith many more qubits. Still\, it's necessary to only track ≈8 Clifford t erms. Our result sheds light on the simulability of operationally relevant \, high T-count quantum circuits with some internal structure.\n\nJoint-Wo rk With: Zhenghao Zhong\n\n UID:040000008200E00074C5B7101A82E008000000006A2C81E0BD70DC01000000000000000 010000000F3D4E39B97AD174EAFEA6D0E40A812C2 SUMMARY:How to Simulate Magic State Cultivation with around 8 Clifford Term s on Average DTSTART;TZID=W. Europe Standard Time:20260427T150000 DTEND;TZID=W. Europe Standard Time:20260427T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Titouan Carette (Institut Polytechnique de Paris)\narXiv: https://arxiv. org/pdf/2508.04296\nZoom link: https://uva-live.zoom.us/j/65093307759\nAbs tract: The discard ZX-calculus is known to be complete and universal for m ixed-state quantum mechanics\, allowing for both quantum and classical pro cesses. However\, if the quantum aspects of ZX-calculus have been explored in depth\, little work has been done on the classical side. In this paper \, we investigate a fragment of discard ZX-calculus obtained by decohering the usual generators of ZX calculus. We show that this calculus is univer sal and complete for affinely supported probability distributions over 𝔽2^n. To do so\, we exhibit a normal form\, mixing ideas from the graph ical linear algebra program and diagrammatic Fourier transforms. Our resul ts both clarify how to handle hybrid classical-quantum processes in the di scard ZX-calculus and pave the way to the picturing of more general random variables and probabilistic processes.\n\nJoint-Work With: Daniela Cojoca ru and Renaud Vilmart\n\n UID:040000008200E00074C5B7101A82E0080000000019FBE59DFC70DC01000000000000000 01000000003153206C4DA8D4EBE3454DEE16C6259 SUMMARY:The Decohered ZX-Calculus DTSTART;TZID=W. Europe Standard Time:20260504T150000 DTEND;TZID=W. Europe Standard Time:20260504T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: José A Bolanos\n\nGitHub: https://github.com/tqec/top ologiq\nZoom link: https://uva-live.zoom.us/j/65093307759\nAbstract: TBA\n \n UID:040000008200E00074C5B7101A82E00800000000975268565870DC01000000000000000 010000000EC2D9FCBAC3AA54EAF2B738AA4B36A8A SUMMARY:Back and Forth between ZX and Lattice Surgery Representations of Qu antum Circuits Using PyZX\, Topologiq\, and TQEC DTSTART;TZID=W. Europe Standard Time:20260511T150000 DTEND;TZID=W. Europe Standard Time:20260511T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:1 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:1 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Maximilian Schweikart\narXiv: https://arxiv.org/pdf/2603.19522\nZoom link: https://uva-live.zoom.us/j/6 5093307759\nAbstract: Decoding a quantum error correction code is generall y NP-hard\, but corrections must be applied at a high frequency to suppres s noise successfully. Matchable codes\, like the surface code\, exhibit a special structure that makes it possible to efficiently\, approximately so lve the decoding problem through minimum-weight perfect matching (MWPM). H owever\, this efficiency-enabling property can be lost when constructing i mplementations for fault-tolerant gadgets such as syndrome-extraction circ uits or logical operations.\nIn this work\, we take a circuit-centric pers pective to formalise how the decoding problem changes when applying ZX rew rites to a ZX diagram with a given detector basis. We demonstrate a set of \nrewrites that preserve MWPM-decodability of circuits and show that these matchability-preserving rewrites can be used to fault-tolerantly extract quantum circuits from phase-free ZX diagrams. In particular\, this allows us to build efficiently decodable\, fault-tolerant syndrome-extraction cir cuits for matchable codes.\nJoint-Work With: Linnea Grans-Samuelsson\, Ale ks Kissinger\, and Benjamin Rodatz\n UID:040000008200E00074C5B7101A82E0080000000047D257BD64C8DC01000000000000000 0100000008870CFF289D82147B411553437230368 SUMMARY:Preserving MWPM-Decodability in Fault-Equivalent Rewrites DTSTART;TZID=W. Europe Standard Time:20260518T150000 DTEND;TZID=W. Europe Standard Time:20260518T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT BEGIN:VEVENT DESCRIPTION:Speaker: Richie Yeung\narXiv: ht tps://arxiv.org/pdf/2605.10910\nZoom link: https://uva-live.zoom.us/j/6509 3307759\nAbstract: We use reinforcement learning to synthesize Clifford ci rcuits on all-to-all connected devices. Equipped with a qubit-relabeling e quivariant\, size-agnostic neural architecture and trained via a random-wa lk curriculum\, our agent reduces symplectic Clifford representations to t he identity using elementary column operations. On six-qubit benchmarks\, it finds circuits within one two-qubit gate of optimality in milliseconds and exact optima for 99.2% of instances within seconds. After further trai ning on ten-qubit cases\, it scales to unseen tableaus with up to thirty q ubits and achieves lower average two-qubit gate counts than Qiskit’s Aar onson-Gottesman and greedy Clifford synthesizers.\nJoint-Work With: Aleks Kissinger and Rob Cornish\n UID:040000008200E00074C5B7101A82E0080000000090D75E82EFE3DC01000000000000000 010000000C514035AD9DF6C4CA2BAF40618FF6F14 SUMMARY:Season Finale: Equivariant Reinforcement Learning for Clifford Quan tum Circuit Synthesis DTSTART;TZID=W. Europe Standard Time:20260525T150000 DTEND;TZID=W. Europe Standard Time:20260525T163000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20260811T030612Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:0 LOCATION:https://uva-live.zoom.us/j/65093307759 X-MICROSOFT-CDO-APPT-SEQUENCE:0 X-MICROSOFT-CDO-BUSYSTATUS:BUSY X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:0 X-MICROSOFT-DONOTFORWARDMEETING:FALSE X-MICROSOFT-DISALLOW-COUNTER:FALSE X-MICROSOFT-REQUESTEDATTENDANCEMODE:DEFAULT X-MICROSOFT-ISRESPONSEREQUESTED:FALSE END:VEVENT END:VCALENDAR