Quantum dynamics and control of ultracold molecules in external fields

Goulven Quéméner, N. Balakrishnan, Roman V. Krems

Roman V. Krems

This article reviews the current state of the art in the field of cold and ultracold molecules and demonstrates that chemical reactions, inelastic collisions and dissociation of molecules at subkelvin temperatures can be manipulated with external electric or magnetic fields. The creation of ultracold molecules may allow for spectroscopy measurements with extremely high precision and tests of fundamental symmetries of nature, quantum computation with molecules as qubits, and controlled chemistry. The probability of chemical reactions and collisional energy transfer can be very large at temperatures near zero kelvin. The collision energy of ultracold atoms and molecules is much smaller than perturbations due to interactions with external electric or magnetic fields available in the laboratory. External fields may therefore be used to induce dissociation of weakly bound molecules, stimulate forbidden electronic transitions, suppress the effect of centrifugal barriers in outgoing reaction channels or tune Feshbach resonances that enhance chemical reactivity.

Christophe Pierre, Meystre

J.M. Shaw

Ultracold dipolar molecules present many new and novel properties for studying the quantum dynamics of many-body physics. In particular, large electric dipole moments found in polar molecules can be tuned with external electric fields which provide for precise control over dipole-dipole interactions. JILA's second generation ultracold KRb molecule experiment provides new capabilities for applying external electric fields. Generating these fields requires several stable high-voltage sources in order to precisely control the transitions in ultracold dipolar molecules. This thesis will discuss my work towards creating stable high-voltage sources to be used in the second generation KRb apparatus.

Tim Langen, Giacomo Valtolina, Dajun Wang +1 more

Benjamin L. Brown, Ian A. Walmsley

Coherent femtosecond optical pulses provide a unique means to manipulate the collision process between a pair of ultracold atoms. The capability to arbitrarily shape strong electric fields gives the possibility of dynamically sculpting the system Hamiltonian on the collisional timescale. In this paper we explore theoretically physically intuitive excitation schemes by which a control field can manipulate the vibronic state populations in an ultracold molecular system, with the goal of bringing atom pairs to short ( R < 10 Å) separations where they may form a tightly bound molecule. The microscopic dynamics of individual pairs of colliding atoms under the influence of an external optical field are explored through explicitly time-dependent numerical simulations. The results provide physical justification for the employment of optimal control techniques for the achievement of state-selective formation of ultracold molecules.