Eva Bookjans

Spin-nematic squeezed vacuum in a quantum gas

Squeezed states—which permit precision beyond the scope of Heisenberg’s uncertainty relation—are well established for spin-1/2 particles. Now an elegant demonstration of squeezing in spin-1 condensates generalizes the criteria for squeezed states to higher spin dimensions.

Quantum phase transition in an antiferromagnetic spinor Bose-Einstein condensate.

We have experimentally observed the dynamics of an antiferromagnetic sodium Bose-Einstein condensate quenched through a quantum phase transition. Using an off-resonant microwave field coupling the F = 1 and F = 2 atomic hyperfine levels, we rapidly switched the quadratic energy shift q from positive to negative values. At q = 0, the system undergoes a transition from a polar to antiferromagnetic phase. We measured the dynamical evolution of the population in the F = 1, mF = 0 state in the vicinity of this transition point and observed a mixed state of all 3 hyperfine components for q < 0. We also observed the coarsening dynamics of the instability for q < 0, as it nucleated small domains that grew to the axial size of the cloud.

Strong quantum spin correlations observed in atomic spin mixing.

We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard quantum limit for the corresponding coherent spin states. The spin fluctuations are detected as atom number differences in the spin states using fluorescent imaging that achieves a detection noise floor of 8 atoms per spin component for a probe time of 100 μs.

Photoassociation spectroscopy of a spin-1 Bose-Einstein condensate

We report on the high resolution photoassociation spectroscopy of a

Antiferromagnetic Spatial Ordering in a Quenched One-Dimensional Spinor Gas

^{87}

Relative number squeezing in a spin-1 Bose-Einstein condensate

Rb spin-1 Bose-Einstein condensate to the

Non-equilibrium Spin Domains in Quenched Sodium Spinor Bose-Einstein condensates

1_mathrm{g} (P_{3/2}) v = 152

Non-destructive imaging of sodium spinor Bose-Einstein condensates

excited molecular states. We demonstrate the use of spin dependent photoassociation to experimentally identify the molecular states and their corresponding initial scattering channel. These identifications are in excellent agreement with the eigenvalues of a hyperfine-rotational Hamiltonian. Using the observed spectra we estimate the change in scattering length and identify photoassociation laser light frequency ranges that maximize the change in the spin-dependent mean-field interaction energy.

Detection of Small Spinor Condensates in Optical Traps

We have experimentally observed the emergence of spontaneous antiferromagnetic spatial order in a sodium spinor Bose-Einstein condensate that was quenched through a magnetic phase transition. For negative values of the quadratic Zeeman shift, a gas initially prepared in the F=1, m(F)=0 state collapsed into a dynamically evolving superposition of all three spin projections, m(F)=0, ±1. The quench gave rise to rich, nonequilibrium behavior where both nematic and magnetic spin waves were generated. We characterized the spatiotemporal evolution through two particle correlations between atoms in each pair of spin states. These revealed dramatic differences between the dynamics of the spin correlations and those of the spin populations.