Spectroscopy on Two Coupled Superconducting Flux Qubits

Majer, Johannes; Paauw, F.G.; Haar, A.C.J. ter; Harmans, C.J.P.M.; Mooij, J. E.

doi:10.1103/physrevlett.94.090501

Cited by 240 publications

(231 citation statements)

References 16 publications

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“…[42][43][44][45][46][47][48][49][50]. In these works the basic parameters of qubits and coupling constants have been measured and also some relaxation characteristics of coupled qubits have been studied.…”

Section: Introductionmentioning

confidence: 99%

“…In these works the basic parameters of qubits and coupling constants have been measured and also some relaxation characteristics of coupled qubits have been studied. Rabi-spectroscopy of two coupled qubits both experimentally and theoretically have been investigated in publications 44,45,47,49,50 . Recently different schemes of controlled coupling between two or more qubits have been proposed 48,[51][52][53] .…”

Section: Introductionmentioning

confidence: 99%

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Amplitude spectroscopy of two coupled qubits

2012

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We study the effect of a time-dependent driving field with a large amplitude on a system composed of two coupled qubits (two-level systems). Using the rotating wave approximation (RWA) makes it possible to find simple conditions for resonant excitation of the four-level system. We find that the resonance conditions include the coupling strength between the qubits. Numerical simulations confirm the qualitative conclusions following from the RWA. To reveal the peculiarities of resonant transitions caused by the quasi-level motion and crossing in a periodic driving field, we use Floquet states, which determine the precise intermediate states of the system. Calculating the quasi-energy states of the multi-level system makes it possible to find the transition probabilities and build interference patterns for the transition probabilities. The interference patterns demonstrate the possibility of obtaining various pieces of information about the qubits, since the positions of transition-probability maxima depend on various system parameters, including the coupling strength between the qubits.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Amplitude spectroscopy of two coupled qubits

2012

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“…In this regard there are now several examples of coupled superconducting qubits ͑here the SQUID ring is, to all intents and purposes, a flux qubit͒. These include fixed coupling flux qubits, 17 current biased Josephson-junction qubits that are either coupled capacitively, 18 or via a connecting superconducting loop. 19 Recently, there has even been an example of tripartite quantum entanglement in macroscopic superconducting circuits.…”

Section: Introductionmentioning

confidence: 99%

Quantum downconversion and multipartite entanglement via a mesoscopic superconducting quantum interference device ring

et al. 2005

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In this paper we study, by analogy with quantum optics, the superconducting quantum interference device ͑SQUID͒ ring mediated quantum mechanical interaction of an input electromagnetic field oscillator mode with two or more output oscillator modes at subintegers of the input frequency. We show that through the nonlinearity of the SQUID ring multiphoton downconversion can take place between the input and output modes with the resultant output photons being created in an entangled state. We also demonstrate that the degree of this entanglement can be adjusted by means of a static magnetic flux which controls the strength of the interaction between these modes via the SQUID ring.

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“…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.…”

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confidence: 99%

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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Spectroscopy on Two Coupled Superconducting Flux Qubits

Cited by 240 publications

References 16 publications

Amplitude spectroscopy of two coupled qubits

Amplitude spectroscopy of two coupled qubits

Quantum downconversion and multipartite entanglement via a mesoscopic superconducting quantum interference device ring

Josephson charge qubits: a brief review

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