Quantum noise in bright soliton matterwave interferometry

Haine, Simon A.

doi:10.1088/1367-2630/aab47f

“…For many T = 0 non-equilibrium phenomena it is sufficient to treat this initial condition as a multimode coherent state that is sampled by seeding the initial mean-field condensate wavefunction with on average half an atom of vacuum noise per mode [48]. Zero temperature TW with this initial condition has successfully modelled BEC dynamics in regimes where nonclassical particle correlations become important [49][50][51][52][53][54][55][56][57][58]. For finite-temperature studies, the relevant c-field theory is the stochastic projected Gross-Pitaevskii equation (SPGPE), which describes interactions between degenerate modes of the quantum field with a static thermal reservoir [59].…”

Section: Classical Field Methodologymentioning

confidence: 99%

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Mehdi

¹

,

Bradley

²

,

Hope

³

et al. 2021

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We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier. Specifically, we perform detailed three-dimensional simulations to model the experiment of Kumar et al. in [Phys. Rev. A 95 021602 (2017)], which observed a strong temperature dependence in the timescale of superflow decay in an ultracold Bose gas. Our ab initio numerical approach exploits a classical-field framework that includes thermal fluctuations due to interactions between the superfluid and a thermal cloud, as well as the intrinsic quantum fluctuations of the Bose gas. In the low-temperature regime our simulations provide a quantitative description of the experimental decay timescales, improving on previous numerical and analytical approaches. At higher temperatures, our simulations give decay timescales that range over the same orders of magnitude observed in the experiment, however, there are some quantitative discrepancies that are not captured by any of the mechanisms we explore. Our results suggest a need for further experimental and theoretical studies into superflow stability.

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“…For many T = 0 non-equilibrium phenomena it is sufficient to treat this initial condition as a multimode coherent state that is sampled by seeding the initial mean-field condensate wavefunction with on average half an atom of vacuum noise per mode [47]. Zero temperature TW with this initial condition has successfully modelled BEC dynamics in regimes where nonclassical particle correlations become important [48][49][50][51][52][53][54][55][56][57]. For finite-temperature studies, the relevant c-field theory is the stochastic projected Gross-Pitaevskii equation (SPGPE), which describes interactions between degenerate modes of the quantum field with a static thermal reservoir [58].…”

Section: Classical Field Methodologymentioning

confidence: 99%

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Mehdi,

Bradley,

Hope

et al. 2021

Preprint

0

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We theoretically investigate the stochastic decay of persistent currents in a toroidal ultracold atomic superfluid caused by a perturbing barrier. Specifically, we perform detailed threedimensional simulations to model the experiment of Kumar et al. in [Phys. Rev. A 95 021602 (2017)], which observed a strong temperature dependence in the timescale of superflow decay in an ultracold Bose gas. Our ab initio numerical approach exploits a classical-field framework that includes thermal fluctuations due to interactions between the superfluid and a thermal cloud, as well as the intrinsic quantum fluctuations of the Bose gas. In the low-temperature regime our simulations provide a quantitative description of the experimental decay timescales. At higher temperatures, our simulations give decay timescales that range over the same orders of magnitude observed in the experiment, however there are some quantitative discrepancies. In particular, we find a much larger perturbing barrier strength is required to simulate a particular decay timescale (between ∼0.15µ and ∼0.5µ), as compared to the experiment. We rule out imprecise estimation of simulation parameters, systematic errors in experimental barrier calibration, and shot-to-shot atom number fluctuations as causes of the discrepancy. However our model does not account for technical noise on the trapping lasers, which may have enhanced the superflow decay in the experiment. For the intermediate temperatures studied in the experiment, we also observe some discrepancy in the sensitivity of the decay timescale to small changes in the barrier height, which may be due to the breakdown of our model's validity in this regime.

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“…In this case, we have increased the interaction time for the read-out compared to the state preparation step. Moreover, We also include U 2 = U 1 , which may be applicable in the case when it is not easy to reverse the sign of the interaction constant χ, such as when one is working with bright-solitons [48], or enhanced nonlinear interactions due to state-dependent potentials [9]. Figure 4 shows F c as a function of detection noise for different choices of U 2 when χt 1 = 0.027 (when the metrological gain using the spin squeezing parameter is maximum) and 0.072 (when the QFI is maximum).…”

Section: Robustifying Entanglement Against Detection Noisementioning

confidence: 99%

Robustifying twist-and-turn entanglement with interaction-based readout

Mirkhalaf

¹

,

Nolan

²

,

Haine

³

2018

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The use of multi-particle entangled states has the potential to drastically increase the sensitivity of atom interferometers and atomic clocks. The twist-and-turn (TNT) Hamiltonian can create multiparticle entanglement much more rapidly than the ubiquitous one-axis twisting (OAT) Hamiltonian in the same spin system. In this paper, we consider the effects of detection noise -a key limitation in current experiments -on the metrological usefulness of nonclassical states generated under TNT dynamics. We also consider a variety of interaction-based readouts to maximize their performance. Interestingly, the optimum interaction-based readout is not the obvious case of perfect time reversal.

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Quantum noise in bright soliton matterwave interferometry

Cited by 28 publications

References 60 publications

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Superflow decay in a toroidal Bose gas: The effect of quantum and thermal fluctuations

Robustifying twist-and-turn entanglement with interaction-based readout

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