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The greatest challenge in achieving the high level of control needed for future technologies based on coherent quantum systems is the decoherence induced by the environment. Here, we present an analytical approach that yields explicit…

Quantum Physics · Physics 2015-08-05 Edwin Barnes , Xin Wang , S. Das Sarma

We show how to realize a general quantum circuit involving gates between arbitrary pairs of qubits by means of geometrically local quantum operations and efficient classical computation. We prove that circuit-level local stochastic noise…

Quantum Physics · Physics 2024-02-22 Shin Ho Choe , Robert Koenig

We present a unified approach to analyzing the cost of various quantum error mitigation methods on the basis of quantum estimation theory. By analyzing the quantum Fisher information matrix of a virtual quantum circuit that effectively…

Quantum Physics · Physics 2024-01-31 Kento Tsubouchi , Takahiro Sagawa , Nobuyuki Yoshioka

Charge qubits formed in double quantum dots represent quintessential two-level systems that enjoy both ease of control and efficient readout. Unfortunately, charge noise can cause rapid decoherence, with typical single-qubit gate fidelities…

Mesoscale and Nanoscale Physics · Physics 2019-03-11 Yuan-Chi Yang , S. N. Coppersmith , Mark Friesen

The surface code is a promising candidate for fault-tolerant quantum computation, achieving a high threshold error rate with nearest-neighbor gates in two spatial dimensions. Here, through a series of numerical simulations, we investigate…

Quantum Physics · Physics 2014-02-18 Ashley M. Stephens

Although the emergence of a fully-functional quantum computer may still be far away from today, in the near future, it is possible to have medium-size, special-purpose, quantum devices that can perform computational tasks not efficiently…

Quantum Physics · Physics 2017-06-28 Man-Hong Yung , Xun Gao

Current implementations of superconducting qubits are often limited by the low fidelities of multi-qubit gates. We present a reproducible and runtime-efficient pulse-level approach for calibrating an improved cross-resonance gate…

Quantum Physics · Physics 2023-03-23 David Danin , Felix Tennie

With the intense interest in small, noisy quantum computing devices comes the push for larger, more accurate -- and hence more useful -- quantum computers. While fully fault-tolerant quantum computers are, in principle, capable of achieving…

Quantum Physics · Physics 2022-04-22 Akshaya Jayashankar , My Duy Hoang Long , Hui Khoon Ng , Prabha Mandayam

Noise is the defining feature of the NISQ era, but it remains unclear if noisy quantum devices are capable of quantum speedups. Quantum supremacy experiments have been a major step forward, but gaps remain between the theory behind these…

Quantum Physics · Physics 2022-03-08 Adam Bouland , Bill Fefferman , Zeph Landau , Yunchao Liu

Fidelity is one of the most valuable and commonly used metrics for assessing the performance of quantum circuits on error-prone quantum processors. Several approaches have been proposed to estimate circuit fidelity without executing it on…

In theory, quantum computers can efficiently simulate quantum physics, factor large numbers and estimate integrals, thus solving otherwise intractable computational problems. In practice, quantum computers must operate with noisy devices…

Quantum Physics · Physics 2009-11-10 E. Knill

We consider an approach to fault tolerant quantum computing based on a simple error detecting code operating as the substrate for a conventional surface code. We develop a customised decoder to process the information about the likely…

Quantum Physics · Physics 2019-12-11 Xiaosi Xu , Qi Zhao , Xiao Yuan , Simon C. Benjamin

We study the distribution over measurement outcomes of noisy random quantum circuits in the low-fidelity regime. We show that, for local noise that is sufficiently weak and unital, correlations (measured by the linear cross-entropy…

Quantum Physics · Physics 2021-12-01 Alexander M. Dalzell , Nicholas Hunter-Jones , Fernando G. S. L. Brandão

We introduce crosstalk-robust gate sets, which are obtained using a novel, scalable optimal control problem exploiting locality. Through the suppression of pairwise quantum crosstalk, the gate sets enable robustness that extends to…

Quantum optimal control theory allows to design accurate quantum gates. We employ it to design high-fidelity two-bit gates for Josephson charge qubits in the presence of both leakage and noise. Our protocol considerably increases the…

Quantum Physics · Physics 2009-11-13 Simone Montangero , Tommaso Calarco , Rosario Fazio

This paper proves the threshold result, which asserts that quantum computation can be made robust against errors and inaccuracies, when the error rate, $\eta$, is smaller than a constant threshold, $\eta_c$. The result holds for a very…

Quantum Physics · Physics 2007-05-23 Dorit Aharonov , Michael Ben-Or

Fault-tolerant quantum error correction provides a strategy to protect information processed by a quantum computer against noise which would otherwise corrupt the data. A fault-tolerant universal quantum computer must implement a universal…

Real quantum computers will be subject to complicated, qubit-dependent noise, instead of simple noise such as depolarizing noise with the same strength for all qubits. We can do quantum error correction more effectively if our decoding…

Quantum Physics · Physics 2024-11-20 Alex Fischer , Akimasa Miyake

In the current era of Noisy Intermediate-Scale Quantum (NISQ) technology, the practical use of quantum computers remains inhibited by our inability to aptly decouple qubits from their environment to mitigate computational errors. In this…

Quantum Physics · Physics 2022-05-09 Thomas J. Maldonado , Johannes Flick , Stefan Krastanov , Alexey Galda

Noise and errors are unavoidable in any realistic quantum process, including processes designed to reduce noise and errors in the first place. In particular, quantum thermodynamical protocols for cooling can be significantly affected,…

Quantum Physics · Physics 2026-01-26 Jian Li , Xiaoyang Wang , Marcus Huber , Nicolai Friis , Pharnam Bakhshinezhad