Abstract: A system for scalable, fault-tolerant photonic quantum computing includes multiple optical circuits, multiple photon number resolving detectors (PNRs), a multiplexer, and an integrated circuit (IC). During operation, the optical circuits generate output states via Gaussian Boson sampling (GBS), and the PNRs generate qubit clusters based on the output states. The multiplexer multiplexes the qubit clusters and replaces empty modes with squeezed vacuum states, to generate multiple hybrid resource states. The IC stitches together the hybrid resource states into a higher-dimensional cluster state that includes states for fault-tolerant quantum computation.

Abstract: There is described a method of processing photonic states generally having: propagating photonic states along optical links of an optical circuit having two-mode entangling gates optically coupling pair(s) of the optical links to one another, the two-mode entangling gates actuatable in either an entanglement state or a routing state, and Gaussian detector(s) downstream of one or more of the optical links; receiving a signal indicating breedability statuses associated to the photonic states; and actuating the two-mode entangling gates in either the entanglement state or the routing state based on said breedability statuses, said actuating including i) actuating one of the two-mode entangling gates into the entanglement state when the optical links of the corresponding pair both propagate a breedable photonic state, and ii) actuating another one of the two-mode entangling gates into the routing state when one of the optical links of the corresponding pair propagates a non-breedable photonic state.

Abstract: A method includes receiving initial quantum states of light or a representation thereof at an optical circuit, from a set of sources. The initial quantum states of light include squeezed states of light, approximate squeezed cat states of light, and/or approximate states of light having at least 3 associated peaks. The optical circuit includes at least one programmable beamsplitter and at least one homodyne detector. The method also includes receiving, at the optical circuit, a signal to cause programming of the at least one programmable beamsplitter and the at least one homodyne detector. The programming is based on at the initial quantum states of light, a measurement of the at least one homodyne detector, and/or a user input. The method also includes generating a plurality of Gottesman-Kitaev-Preskill (GKP) quantum states of light by propagating the initial quantum states of light through the programmed beamsplitter(s) and using the programmed homodyne detector(s).

Abstract: A system for scalable, fault-tolerant photonic quantum computing includes multiple optical circuits, multiple photon number resolving detectors (PNRs), a multiplexer, and an integrated circuit (IC). During operation, the optical circuits generate output states via Gaussian Boson sampling (GBS), and the PNRs generate qubit clusters based on the output states. The multiplexer multiplexes the qubit clusters and replaces empty modes with squeezed vacuum states, to generate multiple hybrid resource states. The IC stitches together the hybrid resource states into a higher-dimensional cluster state that includes states for fault-tolerant quantum computation.

Abstract: A method for simulating a bosonic quantum bit (qubit) on a classical computer are described. The method determines a phase space representation of the qubit in the form of a linear combination of Gaussian functions, each of which is characterized by a mean, a covariance matrix, and a weight coefficient determined from user defined energy parameter and qubit class of the qubit. The qubit may be simulated on a classical computer by applying transformations of quantum logic gates and measurements to update the weight coefficient, mean, and covariance matrix of each of the Gaussian functions.

Abstract: A system for scalable, fault-tolerant photonic quantum computing includes multiple optical circuits, multiple photon number resolving detectors (PNRs), a multiplexer, and an integrated circuit (IC). During operation, the optical circuits generate output states via Gaussian Boson sampling (GBS), and the PNRs generate qubit clusters based on the output states. The multiplexer multiplexes the qubit clusters and replaces empty modes with squeezed vacuum states, to generate multiple hybrid resource states. The IC stitches together the hybrid resource states into a higher-dimensional cluster state that includes states for fault-tolerant quantum computation.