Feasibility of single-photon cross-phase modulation using metastable xenon in a high finesse cavity

Abstract

Strong saturated absorption at nanowatt power levels has been demonstrated using metastable xenon in a high-finesse optical cavity. The use of metastable xenon allows a high quality factor of Q=2×10 8 to be achieved at relatively high atomic densities without any contamination or damage to the optical surfaces, which is often a problem when using highdensity rubidium or other alkali atoms. This technique provides a relatively straightforward way to produce nonlinearities at the single-photon level with possible applications in quantum communications and computing.

Saturated absorption at nanowatt power levels using metastable xenon in a high-finesse optical cavity

“…The strong nonlinearity demonstrated in this way is consistent with the ability to generate other forms of optical nonlinearities, such as single-photon cross-phase modulation [12], which would have a number of practical applications [1][2][3]. It was previously shown that comparable cross-phase modulation can be obtained using either a gas of atoms or a single trapped atom [13].…”

“…The observed saturated absorption at these low power levels suggests that this approach should be able to produce other nonlinear optical effects at ultra-low power levels as well. For example, density-matrix calculations show that we should be able to achieve a single-photon cross-phase shift of approximately 20 mrad using our system [12]. That would be sufficient for a number of proposed applications, including quantum computing [2] and quantum key distribution [3].…”

“…1 Nanowatt saturation of the 6s[3⁄2] 2 to 6p[3⁄2] 2 transition has been previously observed using tapered optical fibers [15]. However, the use of a cavity may be more advantageous for producing the single-photon nonlinear phase shifts for use in quantum information processing [12,16].…”

Cross-phase modulation enhancement via a resonating cavity: semiclassical description

“…This proposal satisfies the conditions necessary to realize optical quantum computation using weak nonlinearities as proposed by Munro, et al [30], non-local interferometry as proposed by Kirby and Franson [31,32], and device-independent quantum key distribution [33]. It also supports some recent experimental efforts [34][35][36].…”

Low-power cross-phase modulation in a metastable xenon-filled cavity for quantum-information applications

“…The field amplitude was approximated by a constant value across an effective cavity mode volume, as described in Ref. [23]. The decay and transition rates were calculated using two-photon absorption measurements performed in our lab, combined with published data for the state lifetimes and branching ratios [19][20][21]…”