Indistinguishable photons from a trapped-ion quantum network node

Abstract

Trapped atomic ions embedded in optical cavities are a promising platform to enable long-distance quantum networks and their most far-reaching applications. Here we achieve and analyze photon indistinguishability in a telecom-converted ion-cavity system. First, two-photon interference of cavity photons at their ion-resonant wavelength is observed and found to reach the limits set by spontaneous emission. Second, this limit is shown to be preserved after a two-step frequency conversion replicating a distributed scenario, in which the cavity photons are converted to the telecom C band and then back to the original wavelength. The achieved interference visibility and photon efficiency would allow for the distribution and practical verification of entanglement between ion-qubit registers separated by several tens of kilometers.

Towards a deterministic interface between trapped-ion qubits and travelling photons

“…Indeed, in our current experimental configuration, these spontaneous scattering events would already strongly limit the probability with which two sequentially entangled photons could be generated. Those same spontaneous scattering events also limit the extent to which the emitted photons are indistinguishable, as we [34] and others [56] have recently studied in an ion-cavity system. Sec.…”

“…While reexcitation has no observable effect on the fidelity of our emitter-photon entanglement (Sec. IV), it will reduce the indistinguishability of the photons, as we have recently studied [34]. We define P pure S as the photon collection probability without reexcitation events, which is For the generation of photons, the system is initialised into the state |u, 0 , where |0 is the vacuum Fock state of the cavity.…”

A trapped ion in an optical cavity: numerical study of an optomechanical transition in the few-photon regime

“…These values were chosen so that they display features of the transition of interest and at the same time are numerically tractable and close to the experimentally accessible regime with present technology. Although we do not aim to describe any particular realization, our parameter choices could for instance correspond to calcium ions in the transition at 854 nm, taking κ, U 0 and ω of the order of 2π × 100 kHz [44].…”

Quantum Teleportation between Remote Qubit Memories with Only a Single Photon as a Resource

“…[21]. This makes our scheme easy to implement in comparison to the conventionally employed overlapping of two identical photons on a beam splitter [6,9,11,22]. In combination with the scheme demonstrated in Ref.…”