Transition from phase slips to the Josephson effect in a superfluid 4He weak link

Hoskinson, Emile; Sato, Yuki; Hahn, Inseob; Packard, R. E.

doi:10.1038/nphys190

Cited by 57 publications

(154 citation statements)

References 13 publications

(17 reference statements)

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“…In neutral systems, persistent currents have been observed since the early experiments with superfluid liquid helium (see Ref. [2] and references therein), and have experimented a revival with the advent of Bose-Einstein condensation of ultracold gases. Multiply connected geometries have allowed the generation of long-life currents in Bose-Einstein condensates (BECs) [3][4][5], paving the way for atomtronic devices.…”

Section: Introductionmentioning

confidence: 99%

Persistent currents supported by solitary waves in toroidal Bose-Einstein condensates

et al. 2015

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We analyze the generation of persistent currents in Bose-Einstein condensates of ultracold gases confined in a ring. This phenomenon has been recently investigated in an experiment [Nature 506, 200 (2014)], where hysteresis loops have been observed in the activation of quantized persistent currents by rotating weak links. In this work, we demonstrate the existence of 3D stationary currents with non-quantized angular momentum. They are generated by families of solitary waves that show a continuous variation in the angular momentum, and provide a bridge between different winding numbers. We show that the size of hysteresis loops is determined by the range of existence within the weak link region of solitary waves which configure the energy barrier preventing phase slips. The barrier vanishes when the critical rotation leads winding numbers and solitonic states to a matching configuration. At this point, Landau and Feynman criteria for phase slips meet: the fluid flow reaches the local speed of sound, and stationary vortex lines (which are the building blocks of solitons) can be excited inside the system.

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Section: Introductionmentioning

confidence: 99%

Persistent currents supported by solitary waves in toroidal Bose-Einstein condensates

et al. 2015

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“…A central feature observed long ago with superfluid 4 He currents through an orifice [1] is the occurrence of single 2π phase slips, which collectively decrease the fluid velocity by a quantized amount. More recently, the transition from phase slips to the Josephson regime has been observed by increasing the helium healing length with respect to the size of the orifice [2].…”

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confidence: 99%

“…Broadly speaking, similar configurations allow for the observation of macroscopic phase coherence effects and can lead to a range of important technologies. While superconducting Josephson junctions are already employed in sensors and detectors, their superfluid counterparts can realize ultrasensitive gyroscopes to detect rotations [2]. For instance, a toroidally shaped superfluid weak link provides the building block of a d.c.-SQUID, which is most promising sensing device based on superfluid interference.…”

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confidence: 99%

Vortex-induced phase-slip dissipation in a toroidal Bose-Einstein condensate flowing through a barrier

Piazza¹,

Collins²,

Smerzi³

2009

Phys. Rev. A

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We study superfluid dissipation due to phase slips for a BEC flowing through a repulsive barrier inside a torus. The barrier is adiabatically raised across the annulus while the condensate flows with a finite quantized angular momentum. At a critical height, a vortex moves from the inner region and reaches the barrier to eventually circulate around the annulus. At a higher critical height, an anti-vortex also enters into the torus from the outer region. Both vortex and anti-vortex decrease the total angular momentum by leaving behind a 2π phase slip. When they collide and annihilate or orbit along the same loop, the condensate suffers a global 2π phase slip, and the total angular momentum decreases by one quantum. In hydrodynamic regime, the instability sets in when the local superfluid velocity equals the sound speed inside the barrier region.

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“…This leads to the concept of phase slippage induced by the creation of a singly quantized vortex crossing the barrier or the bridge weakly linking two superfluid bulks, introduced to explain the "ac" Josephson effects of superfluid Helium [8]. An experimental signature of phase-slips during Josephson oscillations has been found as jumps of the macroscopic current between two weakly linked superfluid Helium reservoirs driven by an external induced pressure difference [9]. However, this behavior was observed only far outside the Josephson tunneling regime, whereas in the latter the current shows smooth sinusoidal oscillations.…”

mentioning

confidence: 99%

Phase slips and vortex dynamics in Josephson oscillations between Bose-Einstein condensates

Abad¹,

Guilleumas²,

Mayol³

et al. 2015

EPL

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We study the relation between Josephson dynamics and topological excitations in a dilute BoseEinstein condensate confined in a double-well trap. We show that the phase slips responsible for the self-trapping regime are created by vortex rings entering and annihilating inside the weak-link region or created at the center of the barrier and expanding outside the system. Large amplitude oscillations just before the onset of self-trapping are also strictly connected with the dynamics of vortex rings at the edges of the inter-well barrier. Our results extend and analyze the dynamics of the vortex-induced phase slippages suggested a few decades ago in relation to the "ac" Josephson effect of superconducting and superfluid helium systems. Introduction. Phase coherence and superfluidity are two characteristic and most intriguing features of quantum fluids. Both phenomena are marked by a complexvalued order parameter. The nature of the order parameter is different in superconductors, helium superfluids or ultracold gases, but the most important common feature is a rigid (due to inter-particle interactions) local phase (arising from macroscopic coherence) whose gradient is proportional to the superfluid velocity. This describes a class of universal phenomena such as the quantization of vortices or the stability of persistent currents.

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Transition from phase slips to the Josephson effect in a superfluid 4He weak link

Abstract: The dynamics of flow between two weakly coupled macroscopic quantum reservoirs can be highly counterintuitive. In both superconductors and superfluids,

Cited by 57 publications

References 13 publications

Persistent currents supported by solitary waves in toroidal Bose-Einstein condensates

Persistent currents supported by solitary waves in toroidal Bose-Einstein condensates

Vortex-induced phase-slip dissipation in a toroidal Bose-Einstein condensate flowing through a barrier

Phase slips and vortex dynamics in Josephson oscillations between Bose-Einstein condensates

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