All-optical single-atom photon router controlled by a single photon
A switch activated by a single control photon for routing a single target photon from either of two switch inputs to either of two switch outputs. The device is based on a single quantum emitter, such as an atom, coupled to a fiber-coupled, chip-based optical micro-resonator. A single reflected control photon toggles the switch from high reflection to high transmission mode, with no additional control fields required. The control and target photons are both in-fiber and practically identical, for compatibility with scalable architectures for quantum information processing.
1. A device for storing and reading a circular polarization of a photon and for routing a single target photon by a single control photon, the device comprising:
a waveguide supporting a first electromagnetic mode and a second electromagnetic mode, wherein the first electromagnetic mode is distinct from the second electromagnetic mode, the waveguide coupled to:
a first input port for a photon;
a second input port for a photon;
a first output port for a photon; and
a second output port for a photon;
wherein the first input port is distinct from the second input port and the first output port is distinct from the second output port:
a quantum emitter having:
a first ground state;
a second ground state;
an excited state;
a first transition, between the first ground state and the excited state, the first transition having a first circular polarization; and
a second transition, between the second ground state and the excited state, the second transition having a second circular polarization;
wherein:
the first ground state is distinct from the second ground state;
the first circular polarization is opposite of the second circular polarization;
the first electromagnetic mode couples to the first transition; and the second electromagnetic mode couples to the second transition.
2. The device of claim 1 , wherein the waveguide couples to the quantum emitter via a resonant cavity.
3. The device of claim 2 , wherein the resonant cavity is a micro-resonator.
4. The device of claim 1 , wherein the waveguide is an optical waveguide.
5. The device of claim 1 , wherein the waveguide is a microwave waveguide.
6. The device of claim 1 , wherein the quantum emitter is a Rubidium atom.
7. The device of claim 6 , wherein the Rubidium atom is a 87 Rb atom.
8. The device of claim 1 , wherein the micro-resonator is in a transverse magnetic (TM) mode.
9. The device of claim 2 , wherein the micro-resonator is a microsphere.
10. The device of claim 9 , wherein the microsphere is a silica microsphere.
11. The device of claim 3 , wherein the micro-resonator is a micro-toroid.
12. The device of claim 11 , wherein the micro-toroid is a silica micro-toroid.
13. The device of claim 3 , wherein the micro-resonator is a microdisk.
14. The device of claim 3 , wherein the micro-resonator is a ring resonator.
15. The device of claim 4 , wherein the optical waveguide comprises a tapered nanofiber and the waveguide is coupled to the quantum emitter via a micro-resonator.
16. The device of claim 15 , further comprising a piezo positioning device, for aligning the tapered nanofiber with the micro-resonator.
17. The device of claim 15 , wherein an input port is coupled to the tapered nanofiber by an optical circulator.
18. The device of claim 17 , wherein the optical circulator is further coupled to an output port.
19. The device of claim 18 , wherein the input port is isolated from the output port by the optical circulator.
20. The device of claim 1 , wherein the quantum emitter is selected from a group consisting of: an atom, a nitrogen vacancy center, a superconducting quibit, and a quantum dot.