Many-body decoherence dynamics and optimized operation of a single-photon switch

Abstract

We develop a theoretical framework to characterize the decoherence dynamics due to multi-photon scattering in an all-optical switch based on Rydberg atom induced nonlinearities. By incorporating the knowledge of this decoherence process into optimal photon storage and retrieval strategies, we establish optimized switching protocols for experimentally relevant conditions, and evaluate the corresponding limits in the achievable fidelities. Based on these results we work out a simplified description that reproduces recent experiments ( Nat. Commun. 7 12480 ) and provides a new interpretation in terms of many-body decoherence involving multiple incident photons and multiple gate excitations forming the switch. Aside from offering insights into the operational capacity of realistic photon switching capabilities, our work provides a complete description of spin wave decoherence in a Rydberg quantum optics setting, and has immediate relevance to a number of further applications employing photon storage in Rydberg media.

Photon Subtraction by Many-Body Decoherence

“…In this work, we undertake such an extension of previous two-body applications [38][39][40][41] to multiple gate and source photons. Our experiments performed in this many-body regime indeed reveal clear deviations from previous theories [45,46] for single gate-photon states. Remarkably, it is possible to derive a closed solution of the general many-body problem that accounts for the interplay of coherent photon propagation, strong atomatom interactions and dissipative processes in an exact fashion.…”

“…This scattering, however, does not leave the gate photons unaffected. Each source photon scattered off a blockade sphere carries information about the position of the Rydberg excitation that is causing the blockade [46]. The associated coherence loss from such projective spatial measurements typically leads to strong localization of the original spin wave state, thereby inhibiting its subsequent retrieval.…”

Quantum Reflections of Nonlocal Optical Solitons in a Cold Rydberg Atomic Gas

“…In order to investigate the QR of the probe field, a linear optical potential (called defect potential or defect) must be prepared initially, which can be realized by using the following method. We assume that some gate photons are stored (via a Rydberg-EIT) in the atomic array in another Rydberg state |4 [36,38,[42][43][44][45] by using a gate laser field [with half Rabi frequency Ω g that couples the levels |1 and |2 ; see the inset on the right hand side of Fig. 1(b)] and an assistant laser field (with half Rabi frequency Ω a that couples the levels |2 and |4 ).…”

“…Note that such a scheme for preparing gate photons have been widely employed for realizing all-optical switchers and transistors with Rydberg atoms in Refs. [36,38,[43][44][45], here we use them to produce the attractive defect potential. In this way, a Rydberg defect potential (i.e.…”

Quantum theory of Kerr nonlinearity with Rydberg slow light polaritons

“…In turn, it has recently been proposed to use Rydberg slow light polaritons for the generation of a quantum two qubit gate [18,19], which seem to be in contradiction to the above no-go theorem. In the present manuscript, we resolve this puzzle by demonstrating that the microscopic description of Rydberg polaritons also provides a consistent quantum theory of a Kerr nonlinearity without the necessity to introduce a strong noise term.Rydberg slow light polaritons have emerged as a highly promising candidate to engineer strong interactions between optical photons with a tremendous recent experimental [16,[20][21][22][23][24][25][26][27][28][29][30] and theoretical [19,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] progress. A variety of applications were shown such as a deterministic single photon source [50], an atomphoton entanglement generation [51], as well as a single photon switch [27] and transistors [26,28,29].…”