Observation of Cooper Pairs in a Mesoscopic 2D Fermi Gas

Holten, Marvin; Bayha, Luca; Subramanian, Keerthan; Brandstetter, Sandra; Heintze, Carl; Lunt, Philipp; Preiss, Philipp M.; Jochim, Selim

doi:10.48550/arxiv.2109.11511

Cited by 4 publications

(7 citation statements)

References 28 publications

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“…3(b) with a revised color coding that matches the distribution function. The hyperradial distribution should be observable experimentally by sampling the many-body wavefunction using recently developed single-atom imaging techniques [55,56], thus verifying the conformal symmetry on a microscopy level, with deviations from our predictions (for example, at stronger interactions or for deformed or rotating traps) a signature of anomalous or explicit symmetry breaking. More broadly, the mesoscopic 2D Fermi gas constitutes an experimentally relevant toy model in which the conformal symmetry can be studied exactly using elementary techniques, which provides a new way to address current problems such as conformal non-equilibrium dynamics [26,[66][67][68][69][70][71].…”

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confidence: 64%

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Nonrelativistic Conformal Invariance in Mesoscopic Two-Dimensional Fermi Gases

Bekassy,

Hofmann

2021

Preprint

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Two-dimensional Fermi gases with universal short-range interactions are known to exhibit a quantum anomaly, where a classical scale and conformal invariance is broken by quantum effects at strong coupling. We argue that in a quasi two-dimensional geometry, a conformal window remains at weak interactions. Using degenerate perturbation theory, we verify the conformal symmetry by computing the energy spectrum of mesoscopic particle ensembles in a harmonic trap, which separates into conformal towers formed by so-called primary states and their center-of-mass and breathing-mode excitations, the latter having excitation energies at precisely twice the harmonic oscillator energy. In addition, using Metropolis importance sampling, we compute the hyperradial distribution function of the many-body wavefunctions, which are predicted by the conformal symmetry in closed analytical form. The weakly interacting Fermi gas constitutes a system where the non-relativistic conformal symmetry can be revealed using elementary methods, and our results are testable in current experiments on mesoscopic Fermi gases.

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confidence: 64%

“…To the best of our knowledge, this provides the only setup where the nonrelativistic conformal symmetry can be verified exactly by elementary means. Moreover, the results presented here should be observable in current experiments on interacting few-body 2D Fermi systems [52][53][54][55][56].…”

mentioning

confidence: 64%

Nonrelativistic Conformal Invariance in Mesoscopic Two-Dimensional Fermi Gases

Bekassy,

Hofmann

2021

Preprint

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“…The bound state's energy and conditions for its existence are the same for all three forms because they give rise to the same F P (E b , h) and E rel th . This is a direct consequence of the relation M T M = 1 2×2 holding for the three 2D-type spin-orbit couplings, which ensures the universal forms q 2 ≡ p 2 , Q 2 ≡ P 2 and Q • q ≡ P • p for momentum-dependent terms in the expressions (44) and (22). For the same reason, the singlet component of the bound-state wave function is also the same for all 2D-type spin-orbit couplings, but this universality does not extend to the triplet components as these are sensitive to the particular form of M [see Eqs.…”

Section: Bound-state Properties For 2d-type Spin-orbit Couplingmentioning

confidence: 93%

“…The polarized spin-triplet character of bound states could be probed experimentally by spectroscopic techniques [42,43] or spin-resolved momentum-correlation measurements on the single-particle level in the few-atom regime as recently realised in Ref. [44].…”

Section: Introductionmentioning

confidence: 99%

Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting

2022

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We theoretically study spin-1/2 fermions confined to two spatial dimensions and experiencing isotropic short-range attraction in the presence of both spin-orbit coupling and Zeeman spin splitting -- a prototypical system for developing topological superfluidity in the many-body sector. Exact solutions for two-particle bound states are found to have a triplet contribution that dominates over the singlet part in an extended region of parameter space where the combined Zeeman- and center-of-mass-motion-induced spin-splitting energy is large. The triplet character of dimers is purest in the regime of weak s-wave interaction strength. Center-of-mass momentum is one of the parameters determining the existence of bound states, which we map out for both two- and one-dimensional types of spin-orbit coupling. Distinctive features emerging in the orbital part of the bound-state wave function, including but not limited to its p-wave character, provide observable signatures of unconventional pairing.

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“…A requirement for this to work is to restrict the COM momentum to values smaller than this momentum scale, which can be achieved at low-enough temperatures. The parameter regime with a large triplet component in the bound state could be probed by a fluorescence-imaging approach with single-atom spin and momentum resolution, as recently demonstrated [48]. The ratio of pairs with same and opposite spin would give a clear indication on the number of singlet or triplet pairs in the system.…”

Section: Experimental Detectionmentioning

confidence: 96%

Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting

Ebling,

Zülicke,

Brand

2021

Preprint

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We theoretically study spin-1/2 fermions confined to two spatial dimensions and experiencing isotropic short-range attraction in the presence of both spin-orbit coupling and Zeeman spin splitting -a prototypical system for developing topological superfluidity in the many-body sector. Exact solutions for two-particle bound states are found to have a triplet character that can become dominant in the regime of weak attractive s-wave interaction when the energy scale of spin-orbit coupling is comparable to a combination of the Zeeman and center-of-mass kinetic energies. The center-of-mass momentum is one of the parameters determining the existence of bound states, which we map out for both two-and onedimensional types of spin-orbit coupling. Distinctive features emerging in the orbital part of the bound-state wave function, including but not limited to its p-wave character, provide observable signatures of unconventional pairing.

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Observation of Cooper Pairs in a Mesoscopic 2D Fermi Gas

Cited by 4 publications

References 28 publications

Nonrelativistic Conformal Invariance in Mesoscopic Two-Dimensional Fermi Gases

Nonrelativistic Conformal Invariance in Mesoscopic Two-Dimensional Fermi Gases

Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting

Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting

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