Thermally activated phase slips of one-dimensional Bose gases in shallow optical lattices

Kunimi, Masaya; Danshita, Ippei

doi:10.1103/physreva.95.033637

Cited by 10 publications

(7 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we explain the numerical method used in this work. In the quasi-2D calculations of the GP equation and the Bogoliubov equation, we use the almost same methods as those used in our previous work [26], i.e., the space discretization is performed by the discrete variable representation method [32] (see also the Appendix A) and seeking the unstable stationary solution of the GP equation is based on the pseudoarclength continuation method [33,34] and the Newton method. For the realtime dynamics, we use the pseudospectral method.…”

Section: Model and Methodsmentioning

confidence: 99%

“…The above-mentioned observation of Ref. [14] challenges our common understanding of the superfluidity in the sense that TAPS has been established as a uni- * Electronic address: E-mail: masaya.kunimi@yukawa.kyotou.ac.jp † Present address : Department of Physics, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan versal decay mechanism applicable to various superfluid systems at finite temperatures, such as superfluid 4 He [21,22], superconductors [23], spin superfluids [24], and one-dimensional Bose gases in optical lattices [25,26]. Resolving this puzzle is important also for engineering and controlling the atomtronic circuits, which require quantitative understanding of the persistent current in the presence of repulsive potential barriers [8].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Decay mechanisms of superflow of Bose-Einstein condensates in ring traps

Kunimi

Danshita

2019

Phys. Rev. A

Self Cite

View full text Add to dashboard Cite

We study the supercurrent decay of a Bose-Einstein condensate in a ring trap combined with a repulsive barrier potential. In recent experiments, Kumar et al. [Phys. Rev. A 95, 021602(R) (2017)] have measured the dependence of the decay rate on the temperature and the barrier strength. However, the origin of the decay observed in the experiment remains unclear. We calculate the rate of supercurrent decay due to thermally activated phase slips (TAPS) by using the Kramers formula based on the Gross-Pitaevskii mean-field theory. The resulting decay rate is astronomically small compared to that measured in the experiment, thus excluding the possibility of TAPS as the decay mechanism. Alternatively, we argue that three-body losses can be relevant to the observed decay and predict that one can observe supercurrent decay via TAPS by decreasing the number of atoms. arXiv:1712.09493v4 [cond-mat.quant-gas]

show abstract

Section: Model and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Decay mechanisms of superflow of Bose-Einstein condensates in ring traps

Kunimi

Danshita

2019

Phys. Rev. A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Restricted dimensionality in many-body systems gives rise to phenomena associated with strong fluctuations and strong correlations between particles [1][2][3]. Among these systems of low dimensionality, one dimensional (1D) quantum systems, e.g., quantum wires such as carbon nanotubes [4][5][6][7][8], 1D liquid 3 He and 4 He [9][10][11][12], and ultracold gases trapped in a 1D potential [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], have offered a unique platform for exploring in and out of equilibrium many-body phenomena that cannot be captured within naive mean-field treatments due to significant quantum and thermal fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Fluctuations of squeezing fields beyond the Tomonaga--Luttinger liquid paradigm

Nagao¹,

Mathey²

2020

Preprint

View full text Add to dashboard Cite

The concept of Tomonaga-Luttinger liquids (TLL) on the basis of the free-boson models is ubiquitous in theoretical descriptions of low-energy properties in one-dimensional quantum systems. In this work, we develop a squeezed-field path-integral description for gapless one-dimensional systems beyond the free-boson picture of the TLL paradigm. In the squeezed-field description, the parameter of the Bogoliubov transformation for the TL Hamiltonian becomes a dynamical squeezing field, and its fluctuations give rise to corrections to the free-boson results. We derive an effective nonlinear Lagrangian describing the dispersion relation of the squeezing field, and interactions between the excitations of the TLL and the squeezing modes. Using the effective Lagrangian, we analyze the imaginary-time correlation function of a vertex operator in the non-interacting limit. We show that a side-band branch emerges due to the fluctuation of the squeezing field, in addition to the standard branch of the free-boson model of the TLL paradigm. Furthermore, we perturbatively analyze the spectral function of the density fluctuations for an ultracold Bose gas in one dimension. We evaluate the renormalized values of the phase velocities and spectral weights of the TLL and side-band branches due to the interaction between the TLL and the squeezing modes. At zero temperature, the renormalized dispersion relations are linear in the momentum, but at nonzero temperatures, these acquire a nonlinear dependence on the momentum due to the thermal population of the excitation branches.

show abstract

“…This disagreement could be due to the range of velocities explored, much larger than in the theory, and to the lattice strength, much lower than in the theory [34]. Nevertheless, new theoretical studies performed in the regime of shallow lattices have demonstrated that the experimentally observed v-independent regime is well described by a TAPS mechanism [36]. By predicting the damping rate G induced by thermally activated phase slips in the regime of low velocity and weak interaction, in fact, the theory shows a good agreement with the experimental values, thus suggesting the interpretation of thermal activation in the v ≪ v * regime.…”

Section: B Small Oscillations: Velocity-dependent Quantum Phase Slipsmentioning

confidence: 81%

“…In addition, the diluteness of quantum gases and a precise knowledge of their relevant physical parameters allow one to perform accurate comparisons with theoretical models. During the last decade, there has indeed been an increasing interest in studying phaseslip phenomena in various quantum gas configurations, both experimentally and theoretically [28][29][30][31][32][33][34][35][36]. An incontrovertible evidence of QPS has however not yet been obtained, although recent experiments have given strong indications of their presence.…”

Section: Quantum Phase Slips In Ultracold Quantum Gasesmentioning

confidence: 99%

Quantum phase slips: from condensed matter to ultracold quantum gases

D’Errico

Abbate

Modugno

2017

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

Quantum phase slips are the primary excitations in one-dimensional superfluids and superconductors at low temperatures. They have been well characterized in most condensed-matter systems, and signatures of their existence has been recently observed in superfluids based on quantum gases too. In this review we briefly summarize the main results obtained on the investigation of phase slips from superconductors to quantum gases. In particular we focus our attention on recent experimental results of the dissipation in one-dimensional Bose superfluids flowing along a shallow periodic potential, which show signatures of quantum phase slips. I. QUANTUM PHASE SLIPS IN CONDENSED MATTERThe ability to carry charge or mass currents with zero dissipation is the hallmark of superconductivity and superfluidity. Superconductors and superfluids are characterized by a macroscopic wave function Ψ(r) = |Ψ(r)|e iφ(r) , the order parameter. The amplitude and phase coherence of the order parameter vanish at the transition temperature or at the critical current, where the system goes back to the normal phase. However, also below the critical temperature and the critical current, the phase coherence of the system can be affected by the so-called phase slips, i.e. phase fluctuations of the order parameter, which induce a finite resistance and therefore lead to a destruction of persistent currents.Phase slips have been historically predicted by Little [1] as thermally activated topological defects, but it is now assessed that they may occur even at zero temperature, due to quantum tunneling events [2]. A phase slip event, in fact, is an elementary excitation of the order parameter due to thermal or quantum fluctuations, corresponding to a local suppression of its amplitude and a simultaneous jump of the phase by 2π. As a consequence of the phase slip event, the superfluid metastable state, i. e. a local minimum of the Ginzburg-Landau free energy F [3] with velocity v ∝ ∇φ(x), decays into a state with lower velocity, since the phase has locally unwound [1]. A phase slip can be thermally activated (TAPS) [4][5][6] when the temperature is higher than the free-energy barrier δF between two neighbouring metastable states and the system may overcome the barrier via thermal fluctuations. The nucleation rate of TAPS follows the Arrhenius law Γ ∝ e −δF/kB T [4, 5], making these events extremely improbable for T < ∼ δF/k B . In this latter regime, a second mechanism for the activation of phase slips becomes dominant: quantum tunneling below the free-energy barrier, triggered by quantum fluctuations. This second type of excitations has been called quantum phase slips (QPS) [2]. Since the role of both thermal and quantum fluctuations becomes increasingly important when reducing the dimensionality, these phenomena are particularly relevant for one-dimensional systems.QPS have been observed in different condensed-matter systems, such as superconducting nanowires [7][8][9][10][11] and Josephson junction arrays [12]. In these systems it is typic...

show abstract

Thermally activated phase slips of one-dimensional Bose gases in shallow optical lattices

Cited by 10 publications

References 59 publications

Decay mechanisms of superflow of Bose-Einstein condensates in ring traps

Decay mechanisms of superflow of Bose-Einstein condensates in ring traps

Fluctuations of squeezing fields beyond the Tomonaga--Luttinger liquid paradigm

Quantum phase slips: from condensed matter to ultracold quantum gases

Contact Info

Product

Resources

About