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Quantum computer is extensively used in solving financial problems. Quantum amplitude estimation, an algorithm that aims to estimate the amplitude of a given quantum state, can be utilized to determine the expectation value of bonds as the…

Quantum Physics · Physics 2024-04-09 Jaewoong Heo , Moonjoo Lee

It is not so well-known that measurement-free quantum error correction protocols can be designed to achieve fault-tolerant quantum computing. Despite the potential advantages of using such protocols in terms of the relaxation of accuracy,…

Quantum Physics · Physics 2010-09-02 Gerardo A. Paz-Silva , Gavin K. Brennen , Jason Twamley

We study the speed/fidelity trade-off for a two-qubit phase gate implemented in $^{43}$Ca$^+$ hyperfine trapped-ion qubits. We characterize various error sources contributing to the measured fidelity, allowing us to account for errors due…

Quantum Physics · Physics 2016-08-10 C. J. Ballance , T. P. Harty , N. M. Linke , D. M. Lucas

Designing encoding and decoding circuits to reliably send messages over many uses of a noisy channel is a central problem in communication theory. When studying the optimal transmission rates achievable with asymptotically vanishing error…

Quantum Physics · Physics 2024-11-07 Matthias Christandl , Alexander Müller-Hermes

Quantum computers hold the promise of solving computational problems which are intractable using conventional methods. For fault-tolerant operation quantum computers must correct errors occurring due to unavoidable decoherence and limited…

Quantum error correction (QEC) is often implemented on hardware that experiences biased noise, where dephasing errors occur more frequently than other errors. This has motivated many recent efforts to develop bias-tailored QEC codes, such…

Quantum Physics · Physics 2026-05-28 Arianna Meinking , Julie Campos , Kenneth R. Brown

Fault-tolerant quantum error correction is essential for implementing quantum algorithms of significant practical importance. In this work, we propose a highly effective use of the surface-GKP code, i.e., the surface code consisting of…

Quantum Physics · Physics 2022-02-01 Kyungjoo Noh , Christopher Chamberland , Fernando G. S. L. Brandão

One of the largest obstacles to building a quantum computer is gate error, where the physical evolution of the state of a qubit or group of qubits during a gate operation does not match the intended unitary transformation. Gate error stems…

Quantum Physics · Physics 2018-02-07 Eliot Kapit

We present a set of efficiently implementable logical multi-qubit gates in concatenated quantum error correction codes using parity qubits. In particular, we show how fault-tolerant high-weight rotation gates of arbitrary angle can be…

Quantum Physics · Physics 2025-12-16 Anette Messinger , Christophe Goeller , Wolfgang Lechner

We report new construction of nine-qubit error-correcting code, which introduces two new nine-qubit codes and one new three-qubit code. Because both the new two nine-qubit codes have the normal logical operators, as opposed to the…

Quantum Physics · Physics 2021-11-16 Long Huang , Xiaohua Wu

We compare the effect of single qubit incoherent and coherent errors on the logical error rate of the Steane [[7,1,3]] quantum error correction code by performing an exact full-density-matrix simulation of an error correction step. We find…

Quantum Physics · Physics 2016-11-02 Mauricio Gutiérrez , Conor Smith , Livia Lulushi , Smitha Janardan , Kenneth R. Brown

Quantum computation holds the promise of solving certain complex problems exponentially faster than classical computers. However, the high prevalent noise in current quantum devices impedes the accurate execution of even basic algorithms.…

Quantum Physics · Physics 2026-05-13 Prithviraj Prabhu

Recent experimental advances have made it possible to implement logical multi-qubit transversal gates on surface codes in a multitude of platforms. A transversal controlled-NOT (tCNOT) gate on two surface codes introduces correlated errors…

Quantum Physics · Physics 2025-10-02 Kaavya Sahay , Yingjia Lin , Shilin Huang , Kenneth R. Brown , Shruti Puri

Designing efficient fault tolerance schemes is crucial for building useful quantum computers. Most standard schemes assume no knowledge of the underlying device noise and rely on general-purpose quantum error-correcting (QEC) codes capable…

Quantum Physics · Physics 2025-03-31 Long D. H. My , Akshaya Jayashankar , Prabha Mandayam , Hui Khoon Ng

Semiconductor spin qubits demonstrated single-qubit gates with fidelities up to $99.9\%$ benchmarked in the single-qubit subspace. However, tomographic characterizations reveals non-negligible crosstalk errors in a larger space.…

The design of coupler-based superconducting two-qubit gates simplifies circuit layout and alleviate frequency crowding, thereby enhancing the scalability and flexibility of quantum chips. However, in such architectures, a trade-off often…

Quantum Physics · Physics 2026-04-13 Bo-Xun Deng , Jia-Qi Hu , Cheng-Yun Ding , Zheng-Yuan Xue , Tao Chen

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…

The ultimate goal of quantum error correction is to create logical qubits with very low error rates (e.g. 1e-12) and assemble them into large-scale quantum computers capable of performing many (e.g. billions) of logical gates on many (e.g.…

Quantum Physics · Physics 2025-11-20 Michael E. Beverland , Malcolm Carroll , Andrew W. Cross , Theodore J. Yoder

Two-dimensional (2D) ion crystals have become a promising way to scale up qubit numbers for ion trap quantum information processing. However, to realize universal quantum computing in this system, individually addressed high-fidelity…