Creation, detection, and decoherence of macroscopic quantum superposition states in double-well Bose-Einstein condensates

Abstract

We study the possibility of creating many-particle macroscopic quantum superposition ͑Schrödinger cat͒like states by using a Feshbach resonance to reverse the sign of the scattering length of a Bose-Einstein condensate trapped in a double-well potential. To address the issue of the experimental verification of coherence in the catlike state, we study the revival of the initial condensate state in the presence of environmentally induced decoherence. As a source of decoherence, we consider the interaction between the atoms and the electromagnetic vacuum, due to the polarization induced by an incident laser field. We find that the resulting decoherence is directly related to the rate at which spontaneously scattered photons carry away sufficient information to distinguish between the two atom distributions which make-up the cat state. We show that for a "perfect" cat state, a single scattered photon will bring about a collapse of the superposition, while a less-than-perfect catlike state can survive multiple scatterings before the collapse occurs. In addition, we study the dephasing effect of atom-atom collisions on the catlike states.

Triangular Bose-Hubbard trimer as a minimal model for a superfluid circuit

“…In fact some self-trapping also happens in the numerics of panel (b) due to the finite accuracy of the computer. The same numerical issue is well known with regard to self-trapping in the dimer system [53,54].…”

Macroscopic superposition states of ultracold bosons in a double-well potential

“…Quantum superpositions of matter waves have been observed for few particles, like electrons, but remains a challenging problem for larger objects; experiments with C 60 molecules are in the lead at present in such efforts (see [50,51] and references therein), but ultracold bosons have the potential to go to hundreds or thousands of particles in an MS state. Therefore, there are many theoretical proposals for realizing them in a BEC experiment [15,34,[52][53][54][55][56][57][58][59][60][61][62], and this remains an appealing research topic with deep physical implications. The two-level scenario introduces the possibility to study other initial states with non-zero occupation of the excited level, which could be the key to realize MS states experimentally, as discussed in [34].…”

Tunneling, self-trapping, and manipulation of higher modes of a Bose-Einstein condensate in a double well

“…3 we also plot the curve satisfying z 0 2 = 1 from Eq. (37). To this end, for each pair (V 0 ,γ ) we solve the integrals (7)- (9) and substitute into Eq.…”

“…Ultracold atoms in double wells have been thoroughly studied in the framework of two-mode models, both with an eye towards unveiling Josephson physics [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and as a candidate system to observe macroscopic atomic quantum superpositions [33][34][35][36][37][38][39][40][41][42][43][44]. In this manuscript, we introduce a semiclassical approach that allows one to study effects on the double-well condensate dynamics stemming from a finite population of the excited single-particle states (see Fig.…”