Demonstration of conditional gate operation using superconducting charge qubits

Yamamoto, Tsuyoshi; Pashkin, Yu. A.; Astafiev, O.; Nakamura, Y.; Tsai, Jaw Shen

doi:10.1038/nature02015

Cited by 626 publications

(537 citation statements)

References 15 publications

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“…There are two ways to control coefficients α and β: either change E J 1 by a magnetic field keeping t 1 constant [21], or change t 1 keeping E J 1 constant [62]. The latter case is technically more difficult as the length of the first pulse is changed while the second pulse is fixed.…”

Section: Quantum Logic Gatementioning

confidence: 99%

“…[15], but with one more pulse gate, was also used for the demonstration of conditional gate operation [21]. Having two pulse gates enables us to address each qubit individually.…”

Section: Quantum Logic Gatementioning

confidence: 99%

“…We have performed experiments demonstrating for the first time quantum coherent dynamics of two solid-state qubits with constant coupling [15] as well as quantum logic gate operation [21].…”

Section: Coupled Charge Qubitsmentioning

confidence: 99%

“…Superconducting qubits utilize charge [5][6][7] or flux [8] degrees of freedom, or energy levels quantization in a single current-biased Josephson junction [9,10]. Inter-qubit coupling [15][16][17][18][19][20] and also quantum logic gates [21][22][23] have been reported later. Further progress in the field slowed down due to obvious decoherence issues that are still to be overcome in order to implement a working quantum computer.…”

mentioning

confidence: 99%

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Josephson charge qubits: a brief review

Pashkin

Astafiev

Yamamoto

et al. 2009

Quantum Inf Process

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The field of solid-state quantum computation is expanding rapidly initiated by our original charge qubit demonstrations. Various types of solid-state qubits are being studied, and their coherent properties are improving. The goal of this review is to summarize achievements on Josephson charge qubits. We cover the results obtained in our joint group of NEC Nano Electronics Research Laboratories and RIKEN Advanced Science Institute, also referring to the works done by other groups. Starting from a short introduction, we describe the principle of the Josephson charge qubit, its manipulation and readout. We proceed with coupling of two charge qubits and implementation of a logic gate. We also discuss decoherence issues. Finally, we show how a charge qubit can be used as an artificial atom coupled to a resonator to demonstrate lasing action.

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Section: Quantum Logic Gatementioning

confidence: 99%

“…[15], but with one more pulse gate, was also used for the demonstration of conditional gate operation [21]. Having two pulse gates enables us to address each qubit individually.…”

Section: Quantum Logic Gatementioning

confidence: 99%

Section: Coupled Charge Qubitsmentioning

confidence: 99%

mentioning

confidence: 99%

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Josephson charge qubits: a brief review

Pashkin

Astafiev

Yamamoto

et al. 2009

Quantum Inf Process

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“…We show that their physical properties simplify the implementation of the difficult steps mentioned above. In these systems one may use the charge 14,15,16 or the conjugate phase degree of freedom 17,18 to store and process quantum information. Typically, one adjusts the parameters such that the ground state is (almost) doubly degenerate, and at low energies the system reduces to a qubit.…”

Section: Introductionmentioning

confidence: 99%

Preparation and manipulation of a fault-tolerant superconducting qubit

2007

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We describe a qubit encoded in continuous quantum variables of an rf superconducting quantum interference device. Since the number of accessible states in the system is infinite, we may protect its two-dimensional subspace from small errors introduced by the interaction with the environment and during manipulations. We show how to prepare the fault-tolerant state and manipulate the system. The discussed operations suffice to perform quantum computation on the encoded state, syndrome extraction, and quantum error correction. We also comment on the physical sources of errors and possible imperfections while manipulating the system.

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Superconducting Qubits

Il’ichev

Oelsner

2018

Wiley Encyclopedia of Electrical and Electronics Engineering

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Superconducting qubits were initially developed with the goal of realizing a superposition of macroscopically distinct quantum states by exploiting superconducting circuits. This basic idea resulted from the quantum mechanical description of the Josephson junction, the key element for producing superconducting qubits. Because the phase across a Josephson junction and its charge are canonical conjugates, there are two alternative realizations of superconducting qubits. The first one is based on the charge degree of freedom, termed charge qubit. The second utilizes the phase (or flux) degree of freedom and correspondingly are called phase (flux) qubits. Nowadays, the most robust superconducting qubit is the transmon. In practical applications, quantum state initialization and manipulations are heavily restricted by the quantum coherence of the qubit itself and of the qubit‐based systems. The main source of decoherence is interactions with the environment. Their relatively large values result from the macroscopic size of the quantum bits. Still, their circuit architecture enables the implementation of different types of coupling schemes between superconducting qubits and qubit‐resonator systems. The handling of superconducting quantum structures requires special experimental methods, including qubit fabrication, cooling to milliKelvin temperatures, experimental characterization, and readout. Concerning applications, superconducting qubits are promising candidates for both quantum simulators and universal quantum computing. This article covers a description of basic types of superconducting qubits and gives a general description of their use that includes dissipation and decoherence, coupling schemes, experimental realization, and basic measurement techniques. Finally, their use as building blocks for the realization of quantum computation is discussed.

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Demonstration of conditional gate operation using superconducting charge qubits

Cited by 626 publications

References 15 publications

Josephson charge qubits: a brief review

Josephson charge qubits: a brief review

Preparation and manipulation of a fault-tolerant superconducting qubit

Superconducting Qubits

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