Spectroscopic probes of quantum gases

Chen-Lung Hung

A. I. Safonov, I. I. Safonova, Igor Stanislavovich Yasnikov

We consider nonlinear spectroscopic effects—interaction-enhanced double resonance and spectrum instability—that appear in ultracold quantum gases owing to collisional frequency shift of atomic transitions and, consequently, due to the dependence of the frequencies on the population of various internal states of the particles. Special emphasis is put to two simplest cases, (a) the gas of two-level atoms and (b) double resonance in a gas of three-level bosons, in which the probe transition frequency remains constant.

Barbara Goss Levi

Bogdan Mihaila, Scott A. Crooker, Krastan B. Blagoev +3 more

We theoretically demonstrate that optical measurements of electron spin noise can be a spectroscopic probe of the entangled quantum states of ultracold fermionic atom gases and unambiguously reveal the detailed nature of the underlying interatomic correlations. Different models of the effective interatomic interactions predict entirely new sets of resonances in the spin noise spectrum. Once the correct effective interatomic interaction model is identified, the detailed noise line shapes of the spin noise can be used to constrain this model. We estimate the magnitude of spin noise signals expected in ultracold fermionic atom gases via noise measurements in classical alkali vapors, which demonstrate the feasibility of this approach.

Lei Jiang, Han Pu, Weiping Zhang +1 more

An optical spectroscopic method based on the principle of electromagnetically induced transparency (EIT) is proposed as quite a generic probing tool that provides valuable insights into the nature of Fermi paring in ultracold Fermi gases of two hyperfine states. This technique has the capability of allowing spectroscopic response to be determined in a nearly nondestructive manner and the whole spectrum may be obtained by scanning the probe-laser frequency faster than the lifetime of the sample without re-preparing the atomic sample repeatedly. A quasiparticle picture is constructed to facilitate a simple physical explanation of the pairing signature in the EIT spectra.

Christof Weitenberg