Deterministic entanglement generation from driving through quantum phase transitions

Abstract

Many-body entanglement is often created through system evolution, aided by non-linear interactions between the constituting particles. The very dynamics, however, can also lead to fluctuations and degradation of the entanglement if the interactions cannot be controlled. Here, we demonstrate neardeterministic generation of an entangled twin-Fock condensate of ∼ 11000 atoms by driving a 87 Rb Bose-Einstein condensate undergoing spin mixing through two consecutive quantum phase transitions (QPTs). We directly observe number squeezing of 10.7 ± 0.6 dB and normalized collective spin length of 0.99 ± 0.01. Together, these observations allow us to infer an entanglementenhanced phase sensitivity of ∼ 6 dB beyond the standard quantum limit and an entanglement breadth of ∼ 910 atoms. Our work highlights the power of generating large-scale useful entanglement by taking advantage of the differ-1

Molecular interferometers: effects of Pauli principle on entangled-enhanced precision measurements

“…Particle losses and/or the absence of single-particle resolution in the experiments also render even/odd fluctuations vanishes [5,6]. Nevertheless, the U-shape of the probability distribution, considered in the literature as an indicator for possible entanglement-enhanced phase resolution [4][5][6][7][8], is preserved.…”

“…But the resulting states are yet characterized by uncorrelated particle fluctuations between the modes. Nevertheless, equation (5) is the ground state of a Hamiltonian describing two ultracold interacting Fermi gases in two independent modes with zero tunneling rate between modes, and one would expect that twin Fock states could be generated by some kind of quantum phase transition, as performed with bosonic atoms [7].…”

“…Twin Fock states, i.e. states with two orthogonal modes populated by the same number of particles, have been produced with both, photons [4,5] and ultracold bosonic atoms [6][7][8]. However, entangled-enhanced precision measurements of the resulting interference phase have been performed only in the case of ultracold bosonic atoms [6,8].…”

Multi-parameter estimation with multi-mode Ramsey interferometry

“…, although more generally the state preparation can start from any Zeeman sublevels to reach the same final probability amplitude distribution of the optimal state. Such multi-parameter estimation scheme can be useful when atoms are subjected to different sources of phase shifts simultaneously, as for example, with spin-1 87 Rb atoms dressed by near-resonant microwaves while under a static magnetic field [47,48], or spin-9/2 87 Sr atoms placed in an optical lattice with polarization dependent light shifts, and collisions with background or non-condensed atoms.…”

“…When detection noise is present, we numerically simulate the estimation process of the two parameters q q , 1 2 { } using 10 4 three-mode (spin-1) atoms with a detection resolution (noise) of 14 atoms (typical numbers achievable in cold-atom experiments [47,48]). For each pair of {θ 1 , θ 2 }, we first compute the probability of detecting an atom in the output mode…”