Abstract: Techniques for performing readout and reset of fluxonium qubits are disclosed. When fluxonium hardware components are coupled to a quantum metamaterial through a readout resonator, said components may be dispersively coupled such that a quantum state of the corresponding fluxonium qubit is read out through the quantum metamaterial, and then the state of the fluxonium qubit is subsequently reset in order to proceed with a quantum computation to be performed. Alternatively, when fluxonium hardware components are coupled directly to a quantum metamaterial, a quantum state of a fluxonium qubit is read out using resonance fluorescence, and then may be subsequently reset back to its ground state, also using resonance fluorescence. A width of a passband of the quantum metamaterial, along with frequencies of the control sequences used, may be tuned such that either readout or reset is selectively activated.

Abstract: A system and method for providing quantum entanglement using a hybrid space-fiber quantum network are described. The hybrid space-fiber quantum network includes a communications hub located proximate to an optical ground station and also includes an aerial entangled particle source, such as an entangled photon source attached to a satellite, drone, aircraft, etc. An atmospheric or free-space channel is used to distribute quantum entanglement between optical ground stations that are separated by geographic distances, via the aerial entangled particle source. Also, fiber optic links are connected to the communications hub located proximate to the optical ground station. The communications hub includes optical switches that enable any of the fiber optic links connected to the communications hub to receive or send distributed quantum entanglement to a remotely located recipient endpoint via the atmospheric or free-space channel.

Abstract: High-fidelity measurements of qubits are achieved by increasing a number of measurements taken by use of a swap operation and a readout qubit, deflating a bosonic qubit for which measurement outcomes are affected by single photon/phonon loss events, deflating a bosonic qubit enabling readout in other basis, and evolving the qubit under a Hamiltonian that couples a mode to be measured to another mode where the Hamiltonian is selected from a three wave mixing interaction, and/or a combination of these techniques.

Abstract: High-fidelity measurements of qubits are achieved by increasing a number of measurements taken by use of a swap operation and a readout qubit, deflating a bosonic qubit for which measurement outcomes are affected by single photon/phonon loss events, deflating a bosonic qubit enabling readout in other basis, and evolving the qubit under a Hamiltonian that couples a mode to be measured to another mode where the Hamiltonian is selected from a three wave mixing interaction, and/or a combination of these techniques.

Abstract: Selective frequency dissipation is implemented that enables cooling of energy gap protected qubits such that excited energy states resulting from heating or other undesired processes are returned to a lower excited energy state or a ground state manifold, thus reducing the probability of errors. Also, the selective frequency dissipation inhibits leakage from the energy gap protected qubits when in the ground state.

Abstract: A system and method for providing quantum entanglement using a hybrid space-fiber quantum network are described. The hybrid space-fiber quantum network includes a communications hub located proximate to an optical ground station and also includes an aerial entangled particle source, such as an entangled photon source attached to a satellite, drone, aircraft, etc. An atmospheric or free-space channel is used to distribute quantum entanglement between optical ground stations that are separated by geographic distances, via the aerial entangled particle source. Also, fiber optic links are connected to the communications hub located proximate to the optical ground station. The communications hub includes optical switches that enable any of the fiber optic links connected to the communications hub to receive or send distributed quantum entanglement to a remotely located recipient endpoint via the atmospheric or free-space channel.

Abstract: A system and method for providing quantum entanglement using a hybrid space-fiber quantum network are described. The hybrid space-fiber quantum network includes a communications hub located proximate to an optical ground station and also includes an aerial entangled particle source, such as an entangled photon source attached to a satellite, drone, aircraft, etc. An atmospheric or free-space channel is used to distribute quantum entanglement between optical ground stations that are separated by geographic distances, via the aerial entangled particle source. Also, fiber optic links are connected to the communications hub located proximate to the optical ground station. The communications hub includes optical switches that enable any of the fiber optic links connected to the communications hub to receive or send distributed quantum entanglement to a remotely located recipient endpoint via the atmospheric or free-space channel.

Abstract: A system and method for providing quantum entanglement as a service are described. Intermediate nodes which may be located in trusted or trustless locations are used to distribute quantum entanglement to endpoints, such as endpoints of customers of a quantum entanglement distribution service. The distributed quantum entanglement provides a secure communication path that does not rely on trust placed in an infrastructure or software provider. To distribute the quantum entanglement, intermediate nodes comprising quantum memories are used. Joint measurements are performed on quantum particles of respective entangled quantum pairs received at the intermediate nodes without collapsing superposition states of the particles. This allows for the quantum entanglement to be extended across intermediate nodes while maintaining entanglement and superposition of the entangled quantum particles.

Abstract: A system and method for providing quantum entanglement using a hybrid space-fiber quantum network are described. The hybrid space-fiber quantum network includes a communications hub located proximate to an optical ground station and also includes an aerial entangled particle source, such as an entangled photon source attached to a satellite, drone, aircraft, etc. An atmospheric or free-space channel is used to distribute quantum entanglement between optical ground stations that are separated by geographic distances, via the aerial entangled particle source. Also, fiber optic links are connected to the communications hub located proximate to the optical ground station. The communications hub includes optical switches that enable any of the fiber optic links connected to the communications hub to receive or send distributed quantum entanglement to a remotely located recipient endpoint via the atmospheric or free-space channel.

Abstract: High-fidelity measurements of qubits are achieved by increasing a number of measurements taken by use of a swap operation and a readout qubit, deflating a bosonic qubit for which measurement outcomes are affected by single photon/phonon loss events, deflating a bosonic qubit enabling readout in other basis, and evolving the qubit under a Hamiltonian that couples a mode to be measured to another mode where the Hamiltonian is selected from a three wave mixing interaction, and/or a combination of these techniques.

Abstract: A fault tolerant quantum computer is implemented using hybrid acoustic-electric qubits. A control circuit includes an asymmetrically threaded superconducting quantum interference devices (ATS) that excites excite phonons in a mechanical resonator by driving a storage mode of the mechanical resonator and dissipates phonons from the mechanical resonator via an open transmission line coupled to the control circuit, wherein the open transmission line is configured to absorb photons from a dump mode of the control circuit.

Abstract: A fault tolerant quantum computer is implemented using hybrid acoustic-electric qubits. A control circuit includes an asymmetrically threaded superconducting quantum interference devices (ATS) that excites excite phonons in a mechanical resonator by driving a storage mode of the mechanical resonator and dissipates phonons from the mechanical resonator via an open transmission line coupled to the control circuit, wherein the open transmission line is configured to absorb photons from a dump mode of the control circuit.

Abstract: An optoelectronic transducer comprises a unipolar, intraband active region and a micro-cavity resonator. The resonator includes a 2D array of essentially equally spaced regions that exhibits resonant modes. Each of the spaced regions has a depth that extends through the active region and has an average refractive index that is different from that of the active region. The refractive index contrast, the spacing of the spaced regions, and the dimensions of the spaced regions are mutually adapted so that the array acts as a micro-cavity resonator and so that at least one frequency of the resonant modes of the array falls within the spectrum of an optoelectronic parameter of the active region (i.e., the gain spectrum where the transducer is a laser; the absorption spectrum where the transducer is a photodetector). In a first embodiment, the transducer is an ISB laser, whereas in a second embodiment it is a unipolar, intraband photodetector.