A tunable macroscopic quantum system based on two fractional vortices

Heim, D. M.; Vogel, Karl; Schleich, Wolfgang P.; Koelle, D.; Kleiner, R.; Goldobin, E.

doi:10.1088/1367-2630/15/5/053020

Cited by 4 publications

(2 citation statements)

References 52 publications

(107 reference statements)

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“…The two macroscopically distinct quantum states needed for the JVQ may also be created by local magnetic fields induced by control currents [14,15] or even by residual spurious fields [16]. Other vortex qubit prototypes were suggested in which the double-well potential is produced by two closely implanted defect sites in the insulator layer [17,18] or by two artificially created discontinuities of the Josephson phase [19]. Furthermore, a two-state system has experimentally demonstrated [20] in which the double-well potential for the vortex is created by the competition between the repulsion at the microshort and the pinning by an in-plane magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Development of a Josephson vortex two-state system based on a confocal annular Josephson junction

Monaco

Mygind

Koshelets

2017

Supercond. Sci. Technol.

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We report theoretical and experimental work on the development of a Josephson vortex qubit based on a confocal annular Josephson tunnel junction (CAJTJ). The key ingredient of this geometrical configuration is a periodically variable width that generates a spatial vortex potential with bistable states. This intrinsic vortex potential can be tuned by an externally applied magnetic field and tilted by a bias current. The two-state system is accurately modeled by a one-dimensional sine-Gordon like equation by means of which one can numerically calculate both the magnetic field needed to set the vortex in a given state as well as the vortex depinning currents. Experimental data taken at 4.2 K on high-quality N b/Al-AlOx/N b CAJTJs with an individual trapped fluxon advocate the presence of a robust and finely tunable double-well potential for which reliable manipulation of the vortex state has been classically demonstrated. The vortex is prepared in a given potential by means of an externally applied magnetic field, while the state readout is accomplished by measuring the vortex-depinning current in a small magnetic field. Our proof of principle experiment convincingly demonstrates that the proposed vortex qubit based on CAJTJs is robust and workable.

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Section: Introductionmentioning

confidence: 99%

Development of a Josephson vortex two-state system based on a confocal annular Josephson junction

Monaco

Mygind

Koshelets

2017

Supercond. Sci. Technol.

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“…When the enclosing normal-barrier is short, this EC/N/EC structure resembles a superconducting Josephson junction [47,[49][50][51] but with coherent interlayer tunneling [3,[6][7][8][9][10] ; such structure is also referred to as the excitonic Josephson junction (EJJ). In our previous work of EJJ [52], we found exotic fractional soliton, an object that carries a topological charge of Q≡f 0 /2π, which resembles fractional vortices [53][54][55][56] in 0-κ superconducting Josephson junction [57,58]. This type of topological objects is a potential candidate for fluxor phase-base qubits.…”

Section: Introductionmentioning

confidence: 81%

Single interface effects dominate in exciton-condensate/normal-barrier/exciton-condensate (EC/N/EC) structures of long-barrier

Hsu

2018

New J. Phys.

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We study theoretically the exciton-condensate/normal-barrier/exciton-condensate (EC/N/EC) structures in bilayers with a tunable relative phase f 0 between the two exciton condensates (ECs). It is a setup inspired initially by the superconducting Josephson junction but with a special ingredient added for bilayer systems, namely, the interlayer tunneling. Our results shows that in a EC/N/EC structure of long-barrier, the single Andreev reflection at one EC/N interface dominates-as opposed to the same structure of short-barrier, in which multiple Andreev reflections can be accommodated (similar to the superconducting Josephson junctions). The single interface effect turns the other EC inert and the system can no longer be understood as a Josephson junction. The supercurrent, however, still occurs at the N/EC interface since the current conservation is still fulfilled with the assistance of the interlayer tunneling in barriers. This exotic mechanism gives rise to only a half portion from a fractional soliton of a doubled topological charge 2Q=f 0 /π (for the same relative phase f 0 ), as opposed to a full portion fraction soliton of charge Q=f 0 /2π in the structures of short-barriers. We predict the current phase relation for the EC/N/EC structures of long-barriers which can be tested experimentally.

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The sine-Gordon Equation in Josephson-Junction Arrays

Mazo

Ustinov

2014

Nonlinear Systems and Complexity

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A tunable macroscopic quantum system based on two fractional vortices

Cited by 4 publications

References 52 publications

Development of a Josephson vortex two-state system based on a confocal annular Josephson junction

Development of a Josephson vortex two-state system based on a confocal annular Josephson junction

Single interface effects dominate in exciton-condensate/normal-barrier/exciton-condensate (EC/N/EC) structures of long-barrier

The sine-Gordon Equation in Josephson-Junction Arrays

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