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US 12,554,172 B2Granted
Raster multiplexing in photonic circuits
AssigneePsiquantum, Corp.
InventorHugo Cable
Life of this patent
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Abstract
Circuits and methods that implement multiplexing for photons propagating in waveguides are disclosed, in which an input photon received on a selected one of a set of input waveguides can be selectably routed to one of a set of output waveguides. The output waveguide can be selected on a rotating or cyclic basis, in a fixed order, and the input waveguide can be selected based at least in part on which one(s) of a set of input waveguides is (are) currently propagating a photon.
Claims19
A system comprising:
- a multiplexer circuit having:
- a plurality of input paths to receive photonic qubits;
- a plurality of output paths including a first subset of output paths having a number (R) of output paths and a second subset of output paths having the number R of output paths, wherein R is at least 2;
- and
- an optical switching network coupled between the input paths and the output paths, the optical switching network comprising a plurality of active optical switches arranged to selectably couple a photonic qubit from any one of the input paths to any one of the output paths;
- a plurality of downstream circuits, each downstream circuit having a first input port and a second input port;
- a first optical switching circuit having a set of R input paths coupled to the first subset of the output paths of the multiplexer circuit and a plurality of output paths coupled to the first input ports of the downstream circuits via delay circuits that introduce different amounts of delay;
- a second optical switching circuit having a set of R input paths coupled to a second subset of the output paths of the multiplexer circuit and a plurality of output paths coupled to the second input ports of the downstream circuits;
- and
- control logic coupled to the multiplexer circuit, the first optical switching circuit, and the second optical switching circuit and configured to control the multiplexer circuit, the first optical switching circuit, and the second optical switching circuit such that a first photonic qubit output on one of the first subset of output paths of the multiplexer circuit and a second photonic qubit output on one of the second subset of output paths of the multiplexer circuit arrive in temporal alignment at the first and second input ports of one of the downstream circuits, the control logic being further configured to:
- receive, for a time bin of a plurality of time bins, an input signal indicative of whether a photonic state encoding a qubit is present on each input path of the multiplexer circuit;
- select, based on the input signal, one of the input paths of the multiplexer circuit as an active input path for the time bin;
- select one of the output paths of the multiplexer circuit as an active output path for the time bin, wherein output paths in the first and second subsets of output paths are selected according to a fixed order such that each output path in the first subset of output paths and each output path in the second subset of output paths is selected as the active output path once during a raster period consisting of 2R consecutive time bins;
- and
- generate control signals to set a state of the optical switching network of the multiplexer circuit for the time bin such that a photon from the active input path is coupled to the active output path.
12 more elements
A method comprising:
- receiving, at a first optical switching circuit, a first group of qubits via a first plurality of optical paths, wherein during each of a plurality of successive time bins in a first set of time bins, each optical path in the first plurality of optical paths receives one qubit of the first group of qubits;
- receiving, at a second optical switching circuit, a second group of qubits via a second plurality of optical paths, wherein during each of a plurality of successive time bins in a second set of time bins subsequent to the first set of time bins, each optical path in the second plurality of optical paths receives one qubit of the second group of qubits;
- identifying a target pairing between a first qubit in the first group of qubits and a second qubit in the second group of qubits;
- routing, by the first optical switching circuit, the first qubit to a selected one of a plurality of downstream circuits via one of a plurality of output paths of the first optical switching circuit, wherein different ones of the output paths of the first optical switching circuit incorporate different amounts of delay;
- and
- routing, by the second optical switching circuit, the second qubit to the selected one of the plurality of downstream circuits via one of a plurality of output paths of the second optical switching circuit such that the first qubit and the second qubit arrive at the selected one of the plurality of downstream circuits in temporal alignment.
3 more elements
Dependencies are inferred from the claim text.