Fate of the false vacuum: Towards realization with ultra-cold atoms

Fialko, O.; Opanchuk, Bogdan; Sidorov, Andrei; Drummond, P. D.; Brand, Joachim

doi:10.1209/0295-5075/110/56001

Cited by 67 publications

(95 citation statements)

References 43 publications

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“…For a detailed path integral derivation and additional details, the interested reader can refer to refs. [14][15][16]. Analogous results can also be obtained by working directly with the equations of motion.…”

Section: Effective Relativisitic Scalar Field Dynamicsmentioning

confidence: 91%

“…In this section, we have investigated the effects of Floquet instabilities arising in the analog false vacuum decay proposal of Fialko et al [14,15], which were originally pointed out in Braden et al [16]. The existence of these instabilities leads to a complete break- .…”

Section: Nonlinear Dynamicsmentioning

confidence: 94%

“…One proposal to build such a system uses a two-component dilute gas cold atom Bose-Einstein condensate (BEC) to simulate a relativistic scalar field with a false vacuum potential [14,15]. In this proposal, the false vacua are generated from unstable local maxima by periodically modulating the direct conversion between the two components.…”

Section: Contentsmentioning

confidence: 99%

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Nonlinear dynamics of the cold atom analog false vacuum

Braden

Johnson

Peiris

et al. 2019

J. High Energ. Phys.

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We investigate the nonlinear dynamics of cold atom systems that can in principle serve as quantum simulators of false vacuum decay. The analog false vacuum manifests as a metastable vacuum state for the relative phase in a two-species Bose-Einstein condensate (BEC), induced by a driven periodic coupling between the two species. In the appropriate low energy limit, the evolution of the relative phase is approximately governed by a relativistic wave equation exhibiting true and false vacuum configurations. In previous work, a linear stability analysis identified exponentially growing short-wavelength modes driven by the time-dependent coupling. These modes threaten to destabilize the analog false vacuum. Here, we employ numerical simulations of the coupled Gross-Pitaevski equations (GPEs) to determine the non-linear evolution of these linearly unstable modes. We find that unless a physical mechanism modifies the GPE on short length scales, the analog false vacuum is indeed destabilized. We briefly discuss various physically expected corrections to the GPEs that may act to remove the exponentially unstable modes. To investigate the resulting dynamics in cases where such a removal mechanism exists, we implement a hard UV cutoff that excludes the unstable modes as a simple model for these corrections. We use this to study the range of phenomena arising from such a system. In particular, we show that by modulating the strength of the time-dependent coupling, it is possible to observe the crossover between a second and first order phase transition out of the false vacuum.

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Section: Effective Relativisitic Scalar Field Dynamicsmentioning

confidence: 91%

Section: Nonlinear Dynamicsmentioning

confidence: 94%

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Nonlinear dynamics of the cold atom analog false vacuum

Braden

Johnson

Peiris

et al. 2019

J. High Energ. Phys.

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“…Such oscillonic patterns have been discussed extensively in the cosmology community, e.g., [44][45][46]51], and also recently for coupled BECs [34]. Other variations seem possible as well, such as extending the proposals [66,67] on cold-atom simulations of 'false vacuum' decay to situations with spatial expansion.…”

Section: Formation Of Breathers Out Of Quantum Fluctuationsmentioning

confidence: 96%

Quantum simulation of expanding space–time with tunnel-coupled condensates

Neuenhahn

Marquardt

2015

New J. Phys.

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We consider two weakly interacting quasi-1D condensates of cold bosonic atoms. It turns out that a time-dependent variation of the tunnel-coupling between those condensates is equivalent to the spatial expansion of a one-dimensional toy-Universe, with regard to the dynamics of the relative phase field. The dynamics of this field is governed by the quantum sine-Gordon equation. Thus, this analogy could be used to 'quantum simulate' the dynamics of a scalar, interacting quantum field on an expanding background. We discuss how to observe the 'freezing' of quantum fluctuations during an accelerating expansion in a possible experiment. We also analyze an experimental protocol to study the formation of sine-Gordon breathers in the relative phase field, seeded by quantum fluctuations. IntroductionThe recent progress in coherently controlling systems of cold atoms (e.g., [1-5]), stimulated a lot of research concerned with employing these experimental systems to 'quantum simulate' prototypical quantum manybody models and quantum field theories (e.g., [6,7]). This includes dynamics that is relevant for the early Universe, e.g. the initial acoustic density oscillations (Sakharov oscillations) that determine the structure observed in the cosmic microwave background radiation and which have recently been simulated using a quench in a cloud of cold atoms [8]. Particularly fascinating are ideas concerned with simulating quantum many-body physics on curved space-times ('analog gravity') (see [9][10][11][12][13][14][15][16][17][18][19][20], as well as references therein) connecting concepts and techniques from cosmology and condensed matter.During the past few years, a very versatile platform for analog quantum simulations with cold atoms has been established in the Schmiedmayer group at Vienna: an atom chip holding one or two quasi-1D bosonic condensates [3,[21][22][23]. In this setup, it is possible to tune the trapping potential in a time-dependent fashion, which includes the possibility to modify the tunnel-coupling between two nearby condensates. That has been used experimentally to probe quench physics [24-28] and to control non-equilibrium dynamics [29]. After releasing the trap, the expanding clouds give rise to matter-wave interference that reveals the relative phase between the two condensates. The spatially resolved phase field can be measured for each run of the experiment, and the full statistics [22,30] as well as higher-order correlators [28] have been extracted from the data of many runs. A recent comprehensive overview of this set of experiments can be found in [31]. The opportunities offered by this platform have resulted in a number of theoretical proposals for future experiments, e.g. [32][33][34].In the present work, we argue that a pair of tunnel-coupled, quasi-1D, bosonic condensates can be employed for simulating an interacting, scalar quantum field on top of an expanding 1+1 dimensional space-time (figures 1(a) and (c)). This scalar field is represented by the relative phase field between the condensate...

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“…In particular, we show that 3D SOC in an interacting Bose gas leads to a highly nontrivial phase diagram featuring a tetracritical point, first-order phase transitions, and emergent metastable phases -none of which have been seen in systems with lower-dimensional SOC and/or in the presence of a trapping potential. Thus this system provides opportunities to study ramifications of multicriticality [39] and metastability, including false-vacuum decay and bubble nucleation [40][41][42][43], in ultra-cold-atom experiments. We have also studied the spectrum of elementary excitations and find it to be useful for probing the multitude of phases and phase transitions.…”

mentioning

confidence: 99%

Multicriticality, metastability, and the roton feature in Bose-Einstein condensates with three-dimensional spin-orbit coupling

Liao¹,

Fialko²,

Brand³

et al. 2015

Phys. Rev. A

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We theoretically study homogeneously trapped atomic Bose-Einstein condensates where all three momentum components couple to a pseudo-spin-1/2 degree of freedom. Tuning the anisotropies of spin-orbit coupling and the spin-dependent interactions is shown to provide access to a rich phase diagram with a tetracritical point, first-order phase transitions, and multiple metastable phases of stripe and plane-wave character. The elementary excitation spectrum of the axial plane-wave phase features an anisotropic roton feature and can be used to probe the phase diagram. In addition to providing a versatile laboratory for studying fundamental concepts in statistical physics, the emergence of metastable phases creates new opportunities for observing false-vacuum decay and bubble nucleation in ultra-cold-atom experiments. The possibility to create artificial gauge fields in neutral ultra-cold atom systems [1, 2] has drastically expanded the array of possibilities for highly controlled experimental simulation of quantum many-particle systems [2,3]. In particular, it has become possible to explore effects associated with spin-orbit coupling (SOC) [4] that give rise to intriguing phenomena such as the quantum spin Hall effect [5][6][7][8], new materials classes such as topological insulators and superconductors [7][8][9][10], and exotic quasiparticle excitations such as Majorana fermions [11][12][13]. In bosonic-atom systems, the presence of SOC was found to generate novel ground states that have no known analogues in conventional solid-state materials [14][15][16]. Intense theoretical attention has focused on the many-body physics of spin-orbitcoupled Bose-atom systems in free space [17][18][19][20][21][22][23] and in harmonic traps [24][25][26][27][28][29][30]. To date, only a special type of SOC involving a single Cartesian component of the atoms' momentum has been realized in the lab [31][32][33][34]. However, several proposals exist for creating a Rashbatype SOC in higher dimensions [35][36][37]. Experimental progress is spurred by predictions of an exotic halfvortex phase [24,26] and a striped superfluid phase [15] is systems with two-dimensional Rashba SOC. The threedimensional analogue of Rashba SOC is also interesting because it is expected to stabilize a long-sought Skyrmion mode in the ground state of trapped Bose-Einstein condensates [27,30]. The intriguing possibility to simulate the so-called Weyl SOC has also been suggested [35].Despite the rapid pace of theoretical and experimental studies in the field of spin-orbit-coupled atom gases, the physical properties of an extended interacting Bose system in the presence of three-dimensional (3D) SOC have not yet been considered in any detail. This clearly presents a crucial gap in our basic understanding, as the extended system's behavior constitutes an important benchmark for identifying effects associated solely with trapping potentials. Furthermore, real experimental systems can be designed with a flat-bottom potential to approximate the extended system and give ...

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Fate of the false vacuum: Towards realization with ultra-cold atoms

Cited by 67 publications

References 43 publications

Nonlinear dynamics of the cold atom analog false vacuum

Nonlinear dynamics of the cold atom analog false vacuum

Quantum simulation of expanding space–time with tunnel-coupled condensates

Multicriticality, metastability, and the roton feature in Bose-Einstein condensates with three-dimensional spin-orbit coupling

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