Engineering long-range interactions between ultracold atoms with light

Abstract

Ultracold temperatures in dilute quantum gases opened the way to an exquisite control of matter at the quantum level. Here we focus on the control of ultracold atomic collisions using a laser to engineer their interactions at large interatomic distances. We show that the entrance channel of two colliding ultracold atoms can be coupled to a repulsive collisional channel by the laser light so that the overall interaction between the two atoms becomes repulsive: this prevents them to come close together and to undergo inelastic processes, thus protecting the atomic gases from unwanted losses. We illustrate such an optical shielding mechanism with 39K and 133Cs atoms colliding at ultracold temperature (<1 microkelvin). The process is described in the framework of the dressed-state picture and we then solve the resulting stationary coupled Schrödinger equations. The role of spontaneous emission and photoinduced inelastic scattering is also investigated as possible limitations of the shielding efficiency. We predict an almost complete suppression of inelastic collisions over a broad range of Rabi frequencies and detunings from the 39K D2 line of the optical shielding laser, both within the [0, 200 MHz] interval. We found that the polarization of the shielding laser has a minor influence on this efficiency. This proposal could easily be formulated for other bialkali-metal pairs as their long-range interaction are all very similar to each other.

Comparison of log-derivative and renormalized Numerov methods in low-energy two-body collisions

“…It is because in this basis the less significant potential interactions are treated as the reference potential which determines equations (10) and (11). While dominate hyperfine interaction contributes more to Q in equation (12), which count against the using of large interval.…”

“…Experimentalists have been primarily focused on few-body collisions because of many interesting phenomenons, such as Feshbach resonance [1], quantum interference [3,4] and chemical stereodynamics [5][6][7], that well suited for state-resolved scattering experiments at cold temperature [2]. Consequently, a large variety of time-independent theories preferred in low-energy region are proposed to deal with atom-atom [8][9][10][11][12], atomdimer [13][14][15][16][17] and dimer-dimer collisions [18][19][20].…”

Phase diagram of hard core bosons with anisotropic interactions

“…However, this state of affairs has drastically changed over the past two decades, as optical lattice technology makes it now feasible, using ultracold atoms and molecules, to create artificial many-body systems accurately realizing the physics contained in these models [10][11][12][13][14]. Therefore, one may on the one hand, compare theoretical predictions and experimental detection with a degree of accuracy not attainable in experiments with naturally occurring physical system (e.g., solid helium), thereby probing even subtler aspects of the theory; in addition, the possibility of engineering interactions among cold atoms [15][16][17][18][19] not occurring in ordinary condensed matter (at least not as the dominant interactions) paves the way to the possible observation of novel, exotic phases of matter [20][21][22].…”