Kevin M. Jones

Photoassociation of sodium in a Bose-Einstein condensate.

We form ultracold Na2 molecules by single-photon photoassociation of a Bose-Einstein condensate, measuring the photoassociation rate, linewidth, and light shift of the J = 1, v = 135 vibrational level of the A1 Sigma (+)(u) molecular state. The photoassociation rate constant increases linearly with intensity, even where it is predicted that many-body effects might limit the rate. Our observations are in good agreement with a two-body theory having no free parameters.

Multi-spatial-mode single-beam quadrature squeezed states of light from four-wave mixing in hot rubidium vapor

We present experimental results on the generation of multi-spatial-mode, single-beam, quadrature squeezed light using four-wave mixing in hot Rb vapor. Squeezing and phase-sensitive deamplification are observed over a range of powers and detunings near the (85)Rb D1 atomic transition. We observe -3 dB of vacuum quadrature squeezing, comparable to the best single-spatial mode results previously reported using atomic vapors, however, produced here in multiple spatial modes. We confirm that the squeezing is present in more than one transverse mode by studying the spatial distribution of the noise properties of the field.

Sodium Bose-Einstein condensates in an optical lattice

The phase transition from a superfluid to a Mott insulator has been observed in a {sup 23}Na Bose-Einstein condensate. A dye laser detuned {approx_equal}5 nm red of the Na 3{sup 2}S{yields}3{sup 2}P{sub 1/2} transition was used to form the three-dimensional optical lattice. The heating effects of the small detuning as well as the three-body decay processes constrained the time scale of the experiment. Certain lattice detunings were found to induce a large loss of atoms. These loss features were shown to be due to photoassociation of atoms to vibrational levels in the Na{sub 2} (1){sup 3}{sigma}{sub g}{sup +} state.

Quantum correlated light beams from non-degenerate four-wave mixing in an atomic vapor: the D1 and D2 lines of 85Rb and 87Rb.

We present experimental results showing that quantum correlated light can be produced using non-degenerate, off-resonant, four-wave mixing (4WM) on both the D1 (795 nm) and D2 (780 nm) lines of (85)Rb and (87)Rb, extending earlier work on the D1 line of (85)Rb. Using this 4WM process in a hot vapor cell to produce bright twin beams, we characterize the degree of intensity-difference noise reduction below the standard quantum limit for each of the four systems. Although each system approximates a double-lambda configuration, differences in details of the actual level structure lead to varying degrees of noise reduction. The observation of quantum correlations on light produced using all four of these systems, regardless of their substructure, suggests that it should be possible to use other systems with similar level structures in order to produce narrow frequency, non-classical beams at a particular wavelength.

All-optical generation and photoassociative probing of sodium Bose–Einstein condensates

We demonstrate an all-optical technique to evaporatively produce sodium Bose?Einstein condensates (BEC). We use a crossed-dipole trap formed from light near 1 ?m, and a simple ramp of the intensity to force evaporation. In addition, we introduce photoassociation as diagnostic of the trap loading process, and show that it can be used to detect the onset of BEC. Finally, we demonstrate the straightforward production of multiple traps with condensates using this technique, and that some control over the spinor state of the BEC is achieved by positioning the trap as well.

Optical saturation of the 13S-23P transition in positronium

The authors report optical saturation of the 13S-23P transition in positronium using ultraviolet light from a frequency-doubled, pulsed dye laser. The increase in ground-state annihilation radiation due to magnetic triplet-singlet mixing in the excited state is used to monitor the transition. From the variation of the annihilation rate as a function of magnetic field, laser power, wavelength and polarisation, the authors verify that the transition is optically saturated, in agreement with model calculations of the system.

Quantum mutual information of an entangled state propagating through a fast-light medium

The long-standing question of information velocity in slow- and fast-light media is investigated by measuring the propagation time of random and correlated noise. The mutual information shared between two modes of an entangled state of light was found to advance when one mode propagates through the fast-light medium.

Sub-natural-linewidth quantum interference features observed in photoassociation of a thermal gas

By driving photoassociation transitions, we form electronically excited molecules (Na{sub 2}{sup )} from ultracold (50-300 {mu}K) Na atoms. Using a second laser to drive transitions from the excited state to a level in the molecular ground state, we are able to split the photoassociation line and observe features with a width smaller than the natural linewidth of the excited molecular state. The quantum interference which gives rise to this effect is analogous to that which leads to electromagnetically induced transparency in three-level atomic {lambda} systems, but here one of the ground states is a pair of free atoms while the other is a bound molecule. The linewidth is limited primarily by the finite temperature of the atoms.

Molecular constants and Rydberg–Klein–Rees (RKR) potential curve for the Na2 1 3Σg− state

Transitions into the doubly excited Na2 1 3Σg− state have been analyzed using near-dissociation expansions (NDE) to represent the vibrational energies and inertial rotational constants, while the centrifugal distortion constants were held fixed at “mechanically consistent” values calculated from the Rydberg–Klein–Rees (RKR) potential implied by those G(v) and Bv functions. The input data cover the range v=0 to 57 and N up to 47, and the fit yields vD=61.41(±0.10) and D0=3385.70(±0.2) cm−1.

Phase sensing beyond the standard quantum limit with a variation on the SU(1,1) interferometer

We present an SU(1,1) interferometer variation where the second nonlinear interaction is replaced with homodyne detection. Sensitivity measurements as a function of phase demonstrate that our device beats the standard quantum limit by 4dB.