Microwave to optical conversion with atoms on a superconducting chip

Abstract

We describe a scheme to coherently convert a microwave photon of a superconducting co-planar waveguide resonator to an optical photon emitted into a well-defined temporal and spatial mode. The conversion is realized by a cold atomic ensemble trapped close the surface of the superconducting atom chip, near the antinode of the microwave cavity. The microwave photon couples to a strong Rydberg transition of the atoms that are also driven by a pair of laser fields with appropriate frequencies and wavevectors for an efficient wave-mixing process. With only several thousand atoms in an ensemble of moderate density, the microwave photon can be completely converted into an optical photon emitted with high probability into the phase matched direction and, e.g. fed into a fiber waveguide. This scheme operates in a free-space configuration, without requiring strong coupling of the atoms to a resonant optical cavity.

Perspectives on quantum transduction

“…Reference [51] provides a detailed analysis of this effect, and proposes a compromise between coupling strength and distance from surfaces. Note, however, that a collective enhancement could be engineered in a resonant, pulsed regime [52]. Even so, it is difficult to continuously excite a dense sample of Rydberg atoms in the multi-photon regime due to the blockade effect [48].…”

Coherent Conversion Between Microwave and Optical Photons—An Overview of Physical Implementations

“…An all‐resonant system may be able to achieve . However, because atomic ensembles naturally offer high cooperativity in the phase‐matched direction, an optical cavity is not vital for high efficiencies . This is in contrast to proposals using single atoms, which would require resonant enhancement.…”

Bidirectional interconversion of microwave and light with thin-film lithium niobate

“…Through high-efficiency electro-optic interface, a hybrid system where quantum information is processed by superconducting circuits and distributed with photonic circuits is one of the most promising schemes to implement largescale quantum networks [12][13][14][15][16]. Various approaches have realized coherent microwave-to-optical conversion, including spin ensembles [17][18][19][20], electro-optomechanics (EOM) [21][22][23][24][25][26][27][28][29][30], rare-earth-doped crystal [31,32], ferromagnetic magnons [33,34], and etc. The highest conversion efficiency of 47% was demonstrated in EOM systems using bulk optical cavity and free-standing megahertz mechanical membranes [25].…”