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We present a scheme designed to suppress the dominant source of infidelity in entangling gates between quantum systems coupled through intermediate bosonic oscillator modes. Such systems are particularly susceptible to residual…

Quantum Physics · Physics 2015-04-01 T. J. Green , M. J. Biercuk

A quantum computer can solve hard problems - such as prime factoring, database searching, and quantum simulation - at the cost of needing to protect fragile quantum states from error. Quantum error correction provides this protection, by…

Isolated spins in semiconductors provide a promising platform to explore quantum mechanical coherence and develop engineered quantum systems. Silicon has attracted great interest as a host material for developing spin qubits because of its…

Mesoscale and Nanoscale Physics · Physics 2015-10-29 Dohun Kim , D. R. Ward , C. B. Simmons , D. E. Savage , M. G. Lagally , Mark Friesen , S. N. Coppersmith , Mark A. Eriksson

To realize fault-tolerant quantum computing, it is necessary to store quantum information in logical qubits with error correction functions, realized by distributing a logical state among multiple physical qubits or by encoding it in the…

Reliable entangling gates for qubits encoded in single-photon states represent a major challenge on the road to scalable quantum computing architectures based on linear optics. In this work, we present two approaches to develop…

Quantum Physics · Physics 2019-03-27 Fabian Ewert , Peter van Loock

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 present theoretical schemes for performing high-fidelity one- and two-qubit pulsed gates for a superconducting flux qubit. The "IBM qubit" consists of three Josephson junctions, three loops, and a superconducting transmission line.…

Quantum Physics · Physics 2008-03-19 Frederico Brito , David P. DiVincenzo , Roger H. Koch , Matthias Steffen

Hyperparallel quantum information processing outperforms its traditional parallel one in terms of channel capacity, low loss rate, and processing speed. We present a way for implementing a robust hyper-parallel optical controlled-phase-flip…

Quantum Physics · Physics 2020-08-05 Hai-Rui Wei , Yan-Bei Zheng , Ming Hua , Guo-Fu Xu

Motivated by recent experiments of Zajac et al. [arXiv:1708.03530], we theoretically describe high-fidelity two-qubit gates using the exchange interaction between the spins in neighboring quantum dots subject to a magnetic field gradient.…

Mesoscale and Nanoscale Physics · Physics 2018-02-22 Maximilian Russ , D. M. Zajac , A. J. Sigillito , F. Borjans , J. M. Taylor , J. R. Petta , Guido Burkard

We present a method of implementing ultrafast two-qubit gates valid for the ultrastrong coupling (USC) and deep strong coupling (DSC) regimes of light-matter interaction, considering state-of-the-art circuit quantum electrodynamics (QED)…

Quantum Physics · Physics 2015-05-30 G. Romero , D. Ballester , Y. M. Wang , V. Scarani , E. Solano

A proposal for a phase gate and a M{\o}lmer-S{\o}rensen (MS) gate in the dressed state basis is presented. In order to perform the multi-qubit interaction, a strong magnetic field gradient is required to couple the phonon-bus to the qubit…

Quantum Physics · Physics 2015-04-15 Itsik Cohen , Seb Weidt , Winfried K. Hensinger , Alex Retzker

High-fidelity two-qubit gates are essential for scalable quantum computing. We present a scheme based on superconducting transmon qubits and a control pulse delivery protocol that enables arbitrary controlled-phase gates modulated solely by…

Recent work on Ising-coupled double-quantum-dot spin qubits in GaAs with voltage-controlled exchange interaction has shown improved two-qubit gate fidelities from the application of oscillating exchange along with a strong magnetic field…

Mesoscale and Nanoscale Physics · Physics 2019-02-06 R. K. L. Colmenar , J. P. Kestner

We demonstrate the experimental realization of a two-qubit M{\o}lmer-S{\o}rensen gate on a magnetic field-insensitive hyperfine transition in $^9$Be$^+$ ions using microwave-near fields emitted by a single microwave conductor embedded in a…

We propose a theoretical protocol to implement multiqubit geometric gates (i.e., the M{\o}lmer-S{\o}rensen gate) using photonic cat-state qubits. These cat-state qubits stored in high-$Q$ resonators are promising for hardware-efficient…

Quantum Physics · Physics 2022-09-05 Ye-Hong Chen , Roberto Stassi , Wei Qin , Adam Miranowicz , Franco Nori

In order to enable semiconductor-based quantum computing with many qubits, issues like residual interqubit coupling and constraints from scalable control hardware need to be tackled to retain the high gate fidelities demonstrated in current…

Quantum Physics · Physics 2021-01-25 Pascal Cerfontaine , René Otten , M. A. Wolfe , Patrick Bethke , Hendrik Bluhm

We report on the implementation of a high fidelity universal gate-set on optical qubits based on trapped $^{88}$Sr$^+$ ions for the purpose of quantum information processing. All coherent operations were performed using a narrow linewidth…

Quantum Physics · Physics 2015-12-09 Nitzan Akerman , Nir Navon , Shlomi Kotler , Yinnon Glickman , Roee Ozeri

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 show that the KLM scheme [Knill, Laflamme and Milburn, Nature {\bf 409}, 46] can be implemented using polarization encoding, thus reducing the number of path modes required by half. One of the main advantages of this new implementation…

Quantum Physics · Physics 2016-09-08 Federico M. Spedalieri , Hwang Lee , Jonathan P. Dowling

We discuss the desired criteria for a two-qubit phase gate and present a method for realising such a gate for quantum computation that is measurement-free and low error. The gate is implemented between qubits via an intermediate bus mode.…

Quantum Physics · Physics 2015-03-20 T. J. Proctor , T. P. Spiller