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In this work, we introduce constructions for non-Abelian qLDPC codes obtained by gauging transversal Clifford gates using measurement and feedback. In particular, we identify two qualitatively different approaches to gauging qLDPC codes to…

Quantum Physics · Physics 2026-02-13 Maine Christos , Chiu Fan Bowen Lo , Vedika Khemani , Rahul Sahay

We introduce group surface codes, which are a natural generalization of the $\mathbb{Z}_2$ surface code, and equivalent to quantum double models of finite groups with specific boundary conditions. We show that group surface codes can be…

Quantum Physics · Physics 2026-03-06 Naren Manjunath , Vieri Mattei , Apoorv Tiwari , Tyler D. Ellison

We propose a universal gate set for quantum computing with all-to-all connectivity and intrinsic robustness to bit-flip errors based on parity encoding. We show that logical controlled phase gate and $R_z$ rotations can be implemented in…

Quantum Physics · Physics 2022-11-03 Michael Fellner , Anette Messinger , Kilian Ender , Wolfgang Lechner

Quantum error mitigation techniques mimic noiseless quantum circuits by running several related noisy circuits and combining their outputs in particular ways. How well such techniques work is thought to depend strongly on how noisy the…

Quantum Physics · Physics 2026-02-12 David Layden , Bradley Mitchell , Karthik Siva

It is a major challenge to construct good quantum codes supporting fault-tolerant (e.g. transversal) non-Clifford gates with low-weight parity-check measurements. In this paper, we construct the first known quantum codes with linear…

Quantum Physics · Physics 2025-10-09 Louis Golowich , Venkatesan Guruswami

Fault tolerance is widely regarded as indispensable for achieving scalable and reliable quantum computing. However, the spacetime overhead required for fault-tolerant quantum computating remains prohibitively large. A critical challenge…

Quantum Physics · Physics 2025-11-26 Pei Zeng , Guo Zheng , Qian Xu , Liang Jiang

A quantum error correcting code protects encoded logical information against errors. Transversal gates are a naturally fault-tolerant way to manipulate logical qubits but cannot be universal themselves. Protocols such as magic state…

Quantum Physics · Physics 2026-02-03 Eric Huang , Pierre-Gabriel Rozon , Arpit Dua , Sarang Gopalakrishnan , Michael J. Gullans

Gradient-based optimization is a key ingredient of variational quantum algorithms, with applications ranging from quantum machine learning to quantum chemistry and simulation. The parameter-shift rule provides a hardware-friendly method for…

Quantum Physics · Physics 2025-10-08 Leonardo Banchi , Dominic Branford , Chetan Waghela

We propose a scalable scheme for optical quantum computing using measurement-induced continuous-variable quantum gates in a loop-based architecture. Here, time-bin-encoded quantum information in a single spatial mode is deterministically…

Quantum Physics · Physics 2017-09-27 Shuntaro Takeda , Akira Furusawa

Random Clifford circuits doped with non Clifford gates exhibit transitions to universal entanglement spectrum statistics[1] and quantum chaotic behavior. In [2] we proved that the injection of $O(n)$ non Clifford gates into a $n$-qubit…

Quantum Physics · Physics 2021-10-05 Salvatore F. E. Oliviero , Lorenzo Leone , Alioscia Hamma

A long-standing challenge in quantum error correction is the infeasibility of universal transversal gates, as shown by the Eastin-Knill theorem. We obtain a necessary and sufficient condition for a quantum code to have universal transversal…

Quantum Physics · Physics 2024-10-28 Pragati Gupta , Andrea Morello , Barry C. Sanders

Quantum error correction is the art of protecting fragile quantum information through suitable encoding and active interventions. After encoding $k$ logical qubits into $n>k$ physical qubits using a stabilizer code, this amounts to…

Quantum Physics · Physics 2025-05-27 Eric J. Kuehnke , Kyano Levi , Joschka Roffe , Jens Eisert , Daniel Miller

Achieving near-term quantum advantage will require accurate estimation of quantum observables despite significant hardware noise. For this purpose, we propose a novel, scalable error-mitigation method that applies to gate-based quantum…

Quantum Physics · Physics 2021-12-01 Piotr Czarnik , Andrew Arrasmith , Patrick J. Coles , Lukasz Cincio

Scalable realisation of quantum computing is reliant on the development of fault tolerant devices. Analysis of quantum error correction protocols typically considers incoherent noise models or noise-free syndrome measurements. While this is…

Quantum Physics · Physics 2026-05-29 Ben Harper , Azar C. Nakhl , Martin Sevior , Muhammad Usman

We consider the problem of fault-tolerant quantum computation in the presence of slow error diagnostics, either caused by measurement latencies or slow decoding algorithms. Our scheme offers a few improvements over previously existing…

Quantum Physics · Physics 2018-01-08 Christopher Chamberland , Pavithran Iyer , David Poulin

We introduce transversal dimension jump, a code-switching protocol for lifted product (LP) quantum low-density parity-check (qLDPC) codes across different chain-complex dimensions, enabling universal fault-tolerant quantum computation with…

Quantum Physics · Physics 2026-03-03 Christine Li , John Preskill , Qian Xu

A long-standing open problem in fault-tolerant quantum computation has been to find a universal set of transversal gates. As three of us proved in arXiv: 0706.1382, such a set does not exist for binary stabilizer codes. Here we generalize…

Quantum Physics · Physics 2011-03-18 Xie Chen , Hyeyoun Chung , Andrew W. Cross , Bei Zeng , Isaac L. Chuang

Quantum error correction is believed to be essential for scalable quantum computation, but its implementation is challenging due to its considerable space-time overhead. Motivated by recent experiments demonstrating efficient manipulation…

Quantum codes are subspaces of the state space of a quantum system that are used to protect quantum information. Some common classes of quantum codes are stabilizer (or additive) codes, non-stabilizer (or non-additive) codes obtained from…

Quantum Physics · Physics 2012-08-27 Hari Dilip Kumar

Qubits encoded in a decoherence-free subsystem and realized in exchange-coupled silicon quantum dots are promising candidates for fault-tolerant quantum computing. Benefits of this approach include excellent coherence, low control…