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Dynamic quantum circuits (DQCs) incorporate mid-circuit measurements and gates conditioned on these measurement outcomes. DQCs can prepare certain long-range entangled states in constant depth, making them a promising route to preparing…

Quantum Physics · Physics 2024-10-14 Faisal Alam , Bryan K. Clark

To achieve scalable universal quantum computing, we need to implement a universal set of logical gates fault-tolerantly, for which the main difficulty lies with non-Clifford gates. We demonstrate that several characteristic features of the…

Quantum Physics · Physics 2025-02-04 Yi-Fei Wang , Yixu Wang , Yu-An Chen , Wenjun Zhang , Tao Zhang , Jiazhong Hu , Wenlan Chen , Yingfei Gu , Zi-Wen Liu

A non-Clifford gate is required for universal quantum computation, and, typically, this is the most error-prone and resource intensive logical operation on an error-correcting code. Small, single-qubit rotations are popular choices for this…

Quantum Physics · Physics 2017-10-05 Ryuji Takagi , Theodore J. Yoder , Isaac L. Chuang

Magic states are a scarce resource for two-dimensional qubit stabilizer codes. Magic state cultivation was recently proposed to reduce the cost of magic state preparation by measuring the transversal Clifford operator of the color code.…

Quantum Physics · Physics 2026-05-11 Bence Hetényi , Benjamin J. Brown , Dominic J. Williamson

Quantum error correction protects logical quantum information against environmental decoherence by encoding logical qubits into entangled states of physical qubits. One of the most important near-term challenges in building a scalable…

Quantum Physics · Physics 2024-10-30 Yifan Hong , Elijah Durso-Sabina , David Hayes , Andrew Lucas

We present a comprehensive and self-contained simplified review of the quantum computing scheme of Phys. Rev. Lett. 98, 190504 (2007), which features a 2-D nearest neighbor coupled lattice of qubits, a threshold error rate approaching 1%,…

Quantum Physics · Physics 2015-03-13 Austin G. Fowler , Ashley M. Stephens , Peter Groszkowski

High-fidelity control of quantum bits is paramount for the reliable execution of quantum algorithms and for achieving fault-tolerance, the ability to correct errors faster than they occur. The central requirement for fault-tolerance is…

We implement all single-qubit operations with fidelities significantly above the minimum threshold required for fault-tolerant quantum computing, using a trapped-ion qubit stored in hyperfine "atomic clock" states of $^{43}$Ca$^+$. We…

We consider a model of quantum computation in which the set of elementary operations is limited to Clifford unitaries, the creation of the state $|0\rangle$ computational basis. In addition, we allow the creation of a one-qubit ancilla in a…

Quantum Physics · Physics 2020-11-07 Sergei Bravyi , Alexei Kitaev

Fault-tolerant logical entangling gates are essential for scalable quantum computing, but are limited by the error rates and overheads of physical two-qubit gates and measurements. To address this limitation, we introduce phantom…

We present numerical simulation results for the 7-to-1 and 15-to-1 state distillation circuits, constructed using transversal CNOTs acting on multiple surface code patches. The distillation circuits are decoded iteratively using the method…

Quantum Physics · Physics 2026-01-28 Kwok Ho Wan

Quantum error correction protects fragile quantum information by encoding it into a larger quantum system. These extra degrees of freedom enable the detection and correction of errors, but also increase the operational complexity of the…

Preparing encoded logical states is the first step in a fault-tolerant quantum computation. Standard approaches based on concatenation or repeated measurement incur a significant time overhead. The Raussendorf-Bravyi-Harrington cluster…

Quantum Physics · Physics 2025-02-12 Thiago Bergamaschi , Yunchao Liu

We propose a novel method to calculate logical error rates in surface codes, assuming independent and identically distributed physical errors. We show how to use our method to analyze hypothetical quantum computers with various…

Quantum Physics · Physics 2026-05-06 Shaked Regev , Daniel Dilley , Andrea Delgado , Ryan Bennink

Quantum low-density parity check (qLDPC) codes are among the leading candidates to realize error-corrected quantum memories with low qubit overhead. Potentially high encoding rates and large distance relative to their block size make them…

Quantum Physics · Physics 2025-11-14 Josias Old , Juval Bechar , Markus Müller , Sascha Heußen

Current quantum technology is approaching the system sizes and fidelities required for quantum error correction. It is therefore important to determine exactly what is needed for proof-of-principle experiments, which will be the first major…

Quantum Physics · Physics 2017-10-04 James R. Wootton , Andreas Peter , Janos R. Winkler , Daniel Loss

Using error correcting codes and fault tolerant techniques, it is possible, at least in theory, to produce logical qubits with significantly lower error rates than the underlying physical qubits. Suppose, however, that the gates that act on…

Quantum Physics · Physics 2016-12-06 M. B. Hastings

Given stabilizer operations and the ability to repeatedly prepare a single-qubit mixed state rho, can we do universal quantum computation? As motivation for this question, "magic state" distillation procedures can reduce the general…

Quantum Physics · Physics 2007-05-23 Ben W. Reichardt

Quantum computing potentially offers exponential speed-ups over classical computing for certain tasks. A central, outstanding challenge to making quantum computing practical is to achieve fault tolerance, meaning that computations of any…

Quantum Physics · Physics 2021-02-01 Jacob Hastrup , Kimin Park , Jonatan Bohr Brask , Radim Filip , Ulrik Lund Andersen

The surface code is one the most promising alternatives for implementing fault-tolerant, large-scale quantum information processing. Its high threshold for single-qubit errors under stochastic noise is one of its most attrative features. We…

Quantum Physics · Physics 2014-10-29 Pejman Jouzdani , E. Novais , I. S. Tupitsyn , Eduardo R. Mucciolo