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Hyper-optimized Quantum Lego Contraction Schedulesquantum-computing

Hyper-optimized Quantum Lego Contraction Schedules

AbstractCalculating the quantum weight enumerator polynomial (WEP) is a valuable tool for characterizing quantum error-correcting (QEC) codes, but it is computationally hard for large or complex codes. The Quantum LEGO (QL) framework provides a tensor network approach for WEP calculation, in some cases offering superpolynomial speedups over brute-force methods, provided the code exhibits area law entanglement, that a good QL layout is used, and an efficient tensor network contraction schedule is found. We analyze the performance of a hyper-optimized contraction schedule framework across QL layouts for diverse stabilizer code families. We find that the intermediate tensors in the QL networks for stabilizer WEPs are often highly sparse, invalidating the dense-tensor assumption of standard cost functions. To address this, we introduce an exact, polynomial-time Sparse Stabilizer Tensor (SST) cost function based on the rank of the parity check matrices for intermediate tensors. The SST cost function correlates perfectly with the true contraction cost, providing a significant advantage over the default cost function, which exhibits large uncertainty. Optimizing contraction schedules using the SST cost function yields substantial performance gains, achieving up to orders of magnitude improvement in actual contraction cost compared to using the dense tensor cost function. Furthermore, the precise cost estimation from the SST function offers an efficient metric to decide whether the QL-based WEP calculation is computationally superior to brute force for a given QL layout. These results, enabled by PlanqTN, a new open-source QL implementation, validate hyper-optimized contraction as a crucial technique for leveraging the QL framework to explore the QEC code design space.Popular summaryQuantum error correction is one of the central tools for making large-scale quantum computers reliable. A major challenge, however, is that the space of possible error-correcting codes is enormo

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Nonclassical nullifiers for quantum hypergraph statesquantum-computing

Nonclassical nullifiers for quantum hypergraph states

AbstractQuantum hypergraph states form a generalisation of the graph state formalism that goes beyond the pairwise (dyadic) interactions imposed by remaining inside the Gaussian approximation. Networks of such states are able to achieve universality for continuous variable measurement based quantum computation with only Gaussian measurements. For normalised states, the simplest hypergraph states are formed from $k$-adic interactions among a collection of $k$ harmonic oscillator ground states. However such powerful resources have not yet been observed in experiments and their robustness and scalability have not been tested. Here we develop and analyse necessary criteria for hypergraph nonclassicality based on simultaneous nonlinear squeezing in the nullifiers of hypergraph states. We put forward an essential analysis of their robustness to realistic scenarios involving thermalisation or loss and suggest several basic proof-of-principle options for experiments to observe nonclassicality in hypergraph states.► BibTeX data@article{Ravikumar2026nonclassical, doi = {10.22331/q-2026-05-05-2091}, url = {https://doi.org/10.22331/q-2026-05-05-2091}, title = {Nonclassical nullifiers for quantum hypergraph states}, author = {Ravikumar, Abhijith and Moore, Darren W. and Filip, Radim}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2091}, month = may, year = {2026} }► References [1] Ri Qu, Juan Wang, Zong-shang Li, and Yan-ru Bao. ``Encoding hypergraphs into quantum states''. Physical Review A 87, 022311 (2013). https:/​/​doi.org/​10.1103/​PhysRevA.87.022311 [2] M. Rossi, M. Huber, D. Bruß, and C. Macchiavello. ``Quantum hypergraph states''. New Journal of Physics 15, 113022 (2013). https:/​/​doi.org/​10.1088/​1367-2630/​15/​11/​113022 [3] Robert Raussendorf and Hans J. Briegel. ``A One-Way Quantum Computer''. Physical Review Letters 86, 5188–5191 (2001). http

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On the structure of higher order quantum mapsquantum-computing

On the structure of higher order quantum maps

AbstractWe study higher order quantum maps in the context of a *-autonomous category of affine subspaces. We show that types of higher order maps can be identified with certain Boolean functions that we call type functions. By an extension of this identification, the algebraic structure of Boolean functions is inherited by some sets of quantum objects including higher order maps. Using the Mobius transform, we assign to each type function a poset whose elements are labelled by subsets of indices of the involved spaces. We then show that the type function corresponds to a comb type if and only if the poset is a chain. We also devise a procedure for decomposition of the poset to a set of basic chains from which the type function is constructed by taking maxima and minima of concatenations of the basic chains in different orders. On the level of higher order maps, maxima and minima correspond to affine mixtures and intersections, respectively.► BibTeX data@article{Jencova2026structureofhigher, doi = {10.22331/q-2026-05-05-2090}, url = {https://doi.org/10.22331/q-2026-05-05-2090}, title = {On the structure of higher order quantum maps}, author = {Jen{\v{c}}ov{\'{a}}, Anna}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2090}, month = may, year = {2026} }► References [1] Luca Apadula, Alessandro Bisio, and Paolo Perinotti. ``No-signalling constrains quantum computation with indefinite causal structure''. Quantum 8, 1241 (2024). arXiv:2202.10214. https:/​/​doi.org/​10.22331/​q-2024-02-05-1241 arXiv:2202.10214 [2] G. Chiribella, G. M. D’Ariano, and P. Perinotti. ``Transforming quantum operations: Quantum supermaps''. EPL (Europhysics Letters) 83, 30004 (2008). arXiv:0804.0180. https:/​/​doi.org/​10.1209/​0295-5075/​83/​30004 arXiv:0804.0180 [3] G. Chiribella, G. M. D'Ariano, and P. Perinotti. ``Quantum circuit architecture''. Phys. Rev. Lett. 101, 0604

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IBM, Cleveland Clinic, and RIKEN simulate massive 12,635 atom protein with quantum computingquantum-computing

IBM, Cleveland Clinic, and RIKEN simulate massive 12,635 atom protein with quantum computing

IBM, Cleveland Clinic, and RIKEN say they simulated a 12,635-atom protein (trypsin) using a hybrid quantum + classical approach, which is way beyond the tiny toy systems we usually hear about. They split the workload so classical supercomputers handle decomposition while quantum processors (up to ~94 qubits) tackle the hard quantum chemistry pieces, then stitch it back together. The scaling jump from ~10 atoms to 12k in a short time is wild, and they claim big accuracy gains too. That said, this still feels like early-stage hybrid HPC doing most of the heavy lifting, not quantum replacing anything yet, but it does look like quantum might finally be inching toward problems that actually matter for drug discovery. submitted by /u/OkReport5065 [link] [comments]

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eleQtron Secures €57 Million in Series A Funding Roundquantum-computing

eleQtron Secures €57 Million in Series A Funding Round

Insider Brief eleQtron raised €57 million in a Series A round to scale its trapped-ion quantum computing technology, signaling growing momentum toward industrial commercialization in the sector. The funding — led by Schwarz Digits with participation from the European Innovation Council and multiple venture and institutional investors — positions the company among Europe’s more prominent quantum players. The company plans to expand production, cloud access, and its MAGIC control technology while leveraging a €54 million order backlog that indicates early commercial demand for its systems. Image: eleQtron leadership team — Jan Henrik Leisse, CEO and Michael Johanning, CTO. (sichtplan) PRESS RELEASE — Deep-tech company eleQtron, a developer of trapped-ion quantum computers, has successfully closed a €57million Series A funding round. This funding round marks a significant step towards the industrial scaling of eleQtron’s technology and underscores the growing momentum in the global race to commercialise quantum computing. It ranks among the largest Series A funding rounds in quantum computing worldwide and clearly positions eleQtron as one of the most ambitious European players in the international arena. The round is led by Schwarz Digits, the IT and digital division of Schwarz Group, an international leader in the retail industry. The EIC Fund of the European Innovation Council (EIC) is also among the key investors. Additional participationcomes from existing investors such as Earlybird, as well as new investors including French VC firm Ankaa Ventures, laser equipment specialist Precitec, and development banks NRW.BANK (Düsseldorf) and IFB Hamburg. The funding package also includes individual grants. eleQtron already has an order backlog of more than €54million, underlining growing commercial demand and placing the company among the few quantum computing players with meaningful commercial traction. The new capital will be used to build scalable production capacity, e

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Is Rigetti Computing a Buy?quantum-computing

Is Rigetti Computing a Buy?

By Keithen Drury – May 5, 2026 at 3:31AM ESTKey PointsRigetti Computing appears to be falling behind its quantum computing peers.Its revenues shrank year over year in 2025's fourth quarter. Rigetti Computing (RGTI +1.14%) is one of the more popular pure-play quantum computing stocks out there. It's a relatively small business, with a market cap hovering around the $5 billion mark. That leaves plenty of room for upside if the company can deliver a go-to option in quantum computing, but reaching the top in this nascent technology will be no easy feat. So, is Rigetti Computing a buy right now? Image source: Getty Images. Rigetti Computing is running behind in a major initiative Quantum computing is a young and extremely complex technology; that makes it particularly difficult for the layman to gauge the potential of the various companies pursuing it. In such cases, it can be wise to take some cues from outside experts. One of the biggest contracts any quantum computing company can be a part of is the Quantum Benchmarking Initiative (QBI), which is being run by DARPA (Defense Advanced Research Projects Agency). This is a public/private collaboration to fast-track quantum computing technology, and while there may not be an ultimate winner, advancing quickly through each stage of the initiative puts companies on the fast track to deploying their quantum solutions in military applications -- a huge opportunity. Nearly 20 companies entered into this opportunity, including other publicly traded players like IonQ (IONQ 0.87%). There are also tech giants such as Google and IBM taking part. There are three stages of the evaluation process, and Rigetti didn't advance to the second one in the most recent round. That showcases Rigetti's product is at the very least behind its competition. Rigetti is working on making changes in hopes to advance to stage B on the second try, but time will tell how that pans out. ExpandNASDAQ: RGTIRigetti ComputingToday's Change(1.14%) $0.20Current

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