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Erasure qubits -- qubits designed to have an error profile that is dominated by detectable leakage errors -- are a promising way to cut down the resources needed for quantum error correction. There have been several recent experiments…

Quantum Physics · Physics 2026-04-07 Filippos Dakis , Shruti Puri , Sophia E. Economou , Edwin Barnes

Quantum error mitigation (QEM) is vital for noisy intermediate-scale quantum (NISQ) devices. While most conventional QEM schemes assume discrete gate-based circuits with noise appearing either before or after each gate, the assumptions are…

Quantum Physics · Physics 2021-03-12 Jinzhao Sun , Xiao Yuan , Takahiro Tsunoda , Vlatko Vedral , Simon C. Bejamin , Suguru Endo

We consider continuous quantum measurement of a superconducting qubit in the circuit QED setup with a moderate bandwidth of the measurement resonator, i.e., when the "bad cavity" limit is not applicable. The goal is a simple description of…

Quantum Physics · Physics 2016-10-26 Alexander N. Korotkov

Achieving high-fidelity two-qubit gates is crucial for spin qubits in silicon double quantum dots. However, the two-qubit gates in experiments are easily suffered from charge noise, which is still a key challenge. Geometric gates which…

Quantum Physics · Physics 2024-09-04 Yong-Yang Lu , Kejin Wei , Chengxian Zhang

In this paper, we propose a new direction of research for the realization of the quantum controlled-not gate based on a technique called ``interaction-free measurement'', where qubits are two-level atoms (or ions) and information is…

Quantum Physics · Physics 2007-05-23 A. A. Methot , Kai Wicker

Cavity quantum electrodynamics (QED) with in-situ tunable interactions is important for developing novel systems for quantum simulation and computing. The ability to tune the dispersive shifts of a cavity QED system provides more…

We propose a fast, scalable all-optical design for arbitrary two-qubit operations for defect qubits in diamond (NV centers) and in silicon carbide, which are promising candidates for room temperature quantum computing. The interaction…

Mesoscale and Nanoscale Physics · Physics 2013-10-29 Dmitry Solenov , Sophia E. Economou , Thomas L. Reinecke

Connecting two half-filled quantum dots to two superconducting leads induces a competition of bonds, with the dots forming either an interdot exchange bond or two individual Yu-Shiba-Rusinov (YSR) screening bonds with the leads. Defining a…

Mesoscale and Nanoscale Physics · Physics 2025-06-11 Gorm Ole Steffensen , Alfredo Levy Yeyati

Quantum error correction plays an important role in fault-tolerant quantum information processing. It is usually difficult to experimentally realize quantum error correction, as it requires multiple qubits and quantum gates with high…

Quantum Physics · Physics 2020-11-10 Qihao Guo , Yuan-Yuan Zhao , Markus Grassl , Xinfang Nie , Guo-Yong Xiang , Tao Xin , Zhang-Qi Yin , Bei Zeng

A generic qubit unitary operator affected by quantum noise is duplicated and inserted in a coherently superposed channel, superposing two paths offered to a probe qubit across the noisy unitary, and driven by a control qubit. A…

Quantum Physics · Physics 2021-10-14 Francois Chapeau-Blondeau

We demonstrate new experimental procedures for measuring small errors in a superconducting quantum bit (qubit). By carefully separating out gate and measurement errors, we construct a complete error budget and demonstrate single qubit gate…

We use quantum process tomography to characterize a full universal set of all-microwave gates on two superconducting single-frequency single-junction transmon qubits. All extracted gate fidelities, including those for Clifford group…

We show an efficient purification protocol in solid-state qubits by replacing the usual bilateral CNOT gate by the bilateral iSWAP gate. We also show that this replacement can be applied to breeding and hashing protocols, which are useful…

Quantum Physics · Physics 2014-01-08 Tetsufumi Tanamoto , Koji Maruyama , Yu-xi Liu , Xuedong Hu , Franco Nori

We propose a scheme for two-qubit gates between a flying photon and an atom in a cavity. The atom-photon gate setup consists of a cavity and a Mach-Zehnder interferometer with doubly degenerate ground and excited state energy levels…

Quantum Physics · Physics 2024-05-21 Omar Nagib , P. Huft , A. Safari , M. Saffman

To implement a set of universal quantum logic gates based on non-Abelian geometric phases, it is a conventional wisdom that quantum systems beyond two levels are required, which is extremely difficult to fulfil for superconducting qubits,…

Quantum Physics · Physics 2015-08-12 Zheng-Yuan Xue , Jian Zhou , Z. D. Wang

Near-term quantum computers are limited by the decoherence of qubits to only being able to run low-depth quantum circuits with acceptable fidelity. This severely restricts what quantum algorithms can be compiled and implemented on such…

We introduce a simple, widely applicable formalism for designing "error-divisible" two qubit gates: a quantum gate set where fractional rotations have proportionally reduced error compared to the full entangling gate. In current noisy…

Quantum Physics · Physics 2021-10-25 David Rodriguez Perez , Paul Varosy , Ziqian Li , Tanay Roy , Eliot Kapit , David Schuster

We present a new experimental protocol for performing universal gates in a register of superconducting qubits coupled by fixed on-chip linear reactances. The qubits have fixed, detuned Larmor frequencies and can remain, during the entire…

Quantum Physics · Physics 2009-11-10 Chad Rigetti , Michel Devoret

We prove the security of a high-capacity quantum key distribution protocol over noisy channels. By using entanglement purification protocol, we construct a modified version of the protocol in which we separate it into two consecutive…

Quantum Physics · Physics 2007-05-23 Xiao-Wei Zhang , Kai Wen , Gui Lu Long

Distant quantum control via quantum gates represents an essential step toward realizing distributed quantum networks. An efficient theoretical protocol for the dual non-local implementation of controlled-not (CNOT) gates between two…

Quantum Physics · Physics 2023-11-17 Chaibata Seida , Abderrahim El Allati , Khadija El Anouz