Creating macroscopic quantum superpositions with Bose-Einstein condensates

Gordon, Dan; Savage, C. M.

doi:10.1103/physreva.59.4623

Cited by 134 publications

(129 citation statements)

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“…Interestingly, the eigenstate for m = −J corresponds to a coherent state, which gives an appropriate description of several physical aspects of the two-mode Bose-Einstein condensate 20 . Its easy to verify that e −θ 2 (a † b−ab † ) |J, m are the eigenstates of the Hamiltonian (1).…”

Section: Resultsmentioning

confidence: 99%

Effects of three-body collisions in a two-mode Bose-Einstein condensate

Sabín

Barberis-Blostein

Hernández

et al. 2015

Journal of Mathematical Physics

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We study the effects of three-body collisions in the physical properties of a two-mode Bose-Einstein condensate. The model introduced here includes two-body and threebody elastic and mode-exchange collisions and can be solved analytically. We will use this fact to show that three-body interactions can produce drastic changes in the probability distribution of the ground state and the dynamics of the relative population. In particular, we find that three-body interactions under certain circumstances may inhibit the collapse of the relative population. 1 arXiv:1407.3365v2 [quant-ph]

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Section: Resultsmentioning

confidence: 99%

Effects of three-body collisions in a two-mode Bose-Einstein condensate

Sabín

Barberis-Blostein

Hernández

et al. 2015

Journal of Mathematical Physics

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“…2 (a)] is formed by a strong (χ/λ ≫ √ N ) two-photon-resonant photoassociation pulse lasting a durationt determined by the solution to the semiclassical approximation [24] for the number of molecules: N/4 = (N/2) tanh 2 ( √ 2N χt ). Interestingly enough, rather than the binomial distribution of particles obtained for dual atomic condensates [14], the trilinear free-bound interaction leads to a squeezed atom-molecule condensate. Such squeezing occurs exactly as in SHG [8], and is a source of many-particle entanglement [22,32].…”

Section: Pacs Number(s)mentioning

confidence: 99%

“…Furthermore, χ is hereafter a real quantity, and ϕ specifies the relative phase between the free-bound and bound-bound lasers. The main difference from the dual atomic condensate problem [13,14] is that the photoassociative coupling is trilinear, and the "tunneling rate", as opposed to being N -independent, therefore scales as √ N . Comparing √ N χ to N λ, the qualitative condition that determines a collision-dominated system is χ/λ < ∼ √ N , where the ratio χ/λ is readily adjustable according to bound-bound intensity I 2 .…”

Section: Pacs Number(s)mentioning

confidence: 99%

“…Hence, we take a dynamical approach [14], which begins with the production of a joint atom-molecule condensate having an "evenly" split population (i.e., N/2 atoms and N/4 molecules), and a realamplitude. Setting the relative phase between the lasers to ϕ = π/2, this state [shown in Fig.…”

Section: Pacs Number(s)mentioning

confidence: 99%

“…The technology of superconducting quantum interference devices (SQUIDs) opened the door to the first proposed macroscopic superposition [3], and the latest SQUID experiments have taken a first step towards demonstrating such a state [4]. Other candidates for creating macroscopic superpositions include nanoscale magnets [5], trapped ions [6], photons in a high-Q cavity [7], second-harmonic generated [8,9] and amplitude-dispersed photons [10], C 60 molecules [11], and two-component Bose-Einstein condensates [12][13][14] (BECs). While it is a matter of contention as to whether or not these states are correctly termed a Schrödinger cat [15], their unambiguous observation would nevertheless invalidate the concept of macroscopic realism.…”

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Superposition of Macroscopic Numbers of Atoms and Molecules

2001

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We theoretically examine photoassociation of a non-ideal Bose-Einstein condensate, focusing on evidence for a macroscopic superposition of atoms and molecules. This problem raises an interest because, rather than two states of a given object, an atom-molecule system is a seemingly impossible macroscopic superposition of different objects. Nevertheless, photoassociation enables coherent intraparticle conversion, and we thereby propose a viable scheme for creating a superposition of a macroscopic number of atoms with a macroscopic number of molecules. PACS number(s): 03.75. Fi, 03.65.Bz, 32.80.Wr In a now famous gedanken experiment [1], Schrödinger highlighted the absurdity of applying quantum theory to macroscopic objects by coupling the fate of a cat to the decay of a radioactive atom, thereby forcing the animal into a superposition of alive and dead. Over the years, this nefarious situation has come to mark the fundamental difference of principle between microscopic quantum mechanics and macroscopic realism: whereas the latter asserts that a system with two (or more) macroscopically distinct states must be in one or the other of these states, the former of course allows for superpositions of different states [2]. It is, however, a somewhat subtle point that marks the difference between macroscopic coherence and a macroscopic superposition. Given a collection of N two-level systems, the macroscopic coherence that leads, e.g., to Josephson-like oscillations, where all N systems tunnel in tandem between the two states, requires only that each system is in a coherent superposition of the two levels, whereas a macroscopic superposition with all of the systems in one or the other of the two states necessarily exhibits an N -body coherence [15]. It is exactly this distinction that warrants the present investigation. Beyond the usual macroscopic superposition of two states of a given object, photoassociation actually leads to a more counterintuitive situation since, like (say) protons and quarks, molecules and atoms are different objects. To the best of our knowledge, the only contemporary systems with a similar potential are a BEC tuned to a Feshbach resonance [23], which would also give a macroscopic atom-molecule superposition, and secondharmonic generation [24] (SHG), which would create, for example, a macroscopic superposition of red and blue photons. These three systems are of course mathematically identical, and the subsequent intramode superposition lies in the possibility for coherent atom-molecule (red-blue photon) conversion. So far, SHG has only yielded intramode phase superpositions between coherent states [9,25], but these results are somewhat ambiguous as they do not differentiate between a coherent superposition and a statistical mixture. In contrast, the present work, based on unitary evolution of a Fock state, clearly demonstrates an intramode superposition of a macroscopic number of atoms with a macroscopic number of molecules. With photoassociation currently [26] on the verge [27] of coherence, t...

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Schrödinger Cat State of a Bose—Einstein Condensate in a Double-Well Potential

Ruostekoski¹

Directions in Quantum Optics

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Creating macroscopic quantum superpositions with Bose-Einstein condensates

Cited by 134 publications

References 15 publications

Effects of three-body collisions in a two-mode Bose-Einstein condensate

Effects of three-body collisions in a two-mode Bose-Einstein condensate

Superposition of Macroscopic Numbers of Atoms and Molecules

Schrödinger Cat State of a Bose—Einstein Condensate in a Double-Well Potential

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