The two Josephson junction flux qubit with large tunneling amplitude

Автор(и)

  • V.I. Shnyrkov B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
  • A.A. Soroka National Science Center "Kharkov Institute of Physics and Technology", Akhiezer Institute for Theoretical Physics 1 Akademicheskaya Str., Kharkov 61108, Ukraine
  • S.I. Melnyk M.K. Yankel Kharkov National University of Radio Electronics, Ministry of Education of Ukraine 4 Lenin Ave., Kharkov 61161, Ukraine

DOI:

https://doi.org/10.1063/1.2967504

Ключові слова:

Josephson flux qubits, coherent superposition of the macroscopic states, the tunneling amplitude.

Анотація

In this paper we discuss solid-state nanoelectronic realizations of Josephson flux qubits with large tunneling amplitude between the two macroscopic states. The latter can be controlled via the height and form of the potential barrier, which is determined by quantum-state engineering of the flux qubit circuit. The simplest circuit of the flux qubit is a superconducting loop interrupted by a Josephson nanoscale tunnel junction. The tunneling amplitude between two macroscopically different states can be essentially increased, by engineering of the qubit circuit, if tunnel junction is replaced by a ScS contact. However, only Josephson tunnel junctions are particularly suitable for large-scale integration circuits and quantum detectors with preset-day technology. To overcome this difficulty we consider here the flux qubit with high-level energy separation between «ground» and «excited» states, which consists of a superconducting loop with two lowcapacitance Josephson tunnel junctions in series. We demonstrate that for real parameters of resonant superposition between the two macroscopic states the tunneling amplitude can reach values greater than 1 K. Analytical results for the tunneling amplitude obtained within semiclassical approximation by instanton technique show good correlation with a numerical solution.

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Опубліковано

2008-07-03

Як цитувати

(1)
Shnyrkov, V.; Soroka, A.; Melnyk, S. The Two Josephson Junction Flux Qubit With Large Tunneling Amplitude. Fiz. Nizk. Temp. 2008, 34, 773-780.

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