Continuous all-optical deceleration and single-photon cooling of molecular beams

Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multilevel numerical simulations of strontium monohydride. These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser. © 2014 American Physical Society

Molecules cooled below the Doppler limit

The ability to cool atoms below the Doppler limit -- the minimum temperature reachable by Doppler cooling -- has been essential to most experiments with quantum degenerate gases, optical lattices and atomic fountains, among many other applications. A broad set of new applications await ultracold molecules, and the extension of laser cooling to molecules has begun. A molecular magneto-optical trap has been demonstrated, where molecules approached the Doppler limit. However, the sub-Doppler temperatures required for most applications have not yet been reached. Here we cool molecules to 50 uK, well below the Doppler limit, using a three-dimensional optical molasses. These ultracold molecules could be loaded into optical tweezers to trap arbitrary arrays for quantum simulation, launched into a molecular fountain for testing fundamental physics, and used to study ultracold collisions and ultracold chemistry

Continuous all-optical deceleration and single-photon cooling of molecular beams

Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multilevel numerical simulations of strontium monohydride. These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser. © 2014 American Physical Society

Magnetic trapping of NH molecules with 20 s lifetimes

Buffer gas cooling is used to trap NH molecules with 1/e lifetimes exceeding 20 s. Helium vapor generated by laser desorption of a helium film is employed to thermalize 105 molecules at a temperature of 500mK in a 3.9 T magnetic trap. Long molecule trapping times are attained through rapid pumpout of residual buffer gas. Molecules experience a helium background gas density below 1 x 1012cm-3. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

Magnetic trapping of atomic nitrogen (N14) and cotrapping of NH (X Σ-3)

We observe magnetic trapping of atomic nitrogen (N14) and cotrapping of ground-state imidogen (N14 H, X Σ-3). Both are loaded directly from a room-temperature beam via buffer gas cooling. We trap approximately 1× 1011 N14 atoms at a peak density of 5× 1011 cm-3 at 550 mK. The 12±4 s 1/e lifetime of atomic nitrogen in the trap is consistent with a model for loss of atoms over the edge of the trap in the presence of helium buffer gas. Cotrapping of N14 and N14 H is accomplished, with 108 NH trapped molecules at a peak density of 108 cm-3. © 2008 The American Physical Society