The generation of entangled photons is provided by two-photon emission by an emission center immersed in an optical microcavity (MC). The MC is designed to reduce or to suppress the emission of single photons at the fundamental emission wavelength (λ.sub.g) of the emitter and increase the emission for the two-photon emission wavelength (2λ.sub.g). A reflector is added only to reflect single photons and will not reflect the biphotons.

A device for quantum information processing is disclosed herein. According to examples, the device comprises a first plurality of confinement regions for confining spinful charge carriers for use as data qudits. The device further comprises a second plurality of confinement regions for confining spinful charge carriers for use as ancillary qudits, each confinement region of the second plurality of confinement regions couplable to measurement apparatus for measuring an ancillary qudit. The device further comprises a third plurality of confinement regions for confining spinful charge carriers, each confinement region of the third plurality of confinement regions situated between a first confinement region of the first plurality of confinement regions and a second confinement region of the second plurality of confinement regions and for use in mediating interactions between a data qudit of the first confinement region and an ancillary qudit of the second confinement region. The device further comprises one or more charge reservoirs. Each confinement region of the third plurality of confinement regions is couplable to a charge reservoir of the one or more charge reservoirs. Methods for operating a device for quantum information processing, and computer-readable media, are also described herein.

A security test logic system can include a non-transitory memory configured to store measurements from a measurement apparatus, the measurement outputs comprising indications of presence or absence of coincidences where particles are detected at more than one detector at substantially the same time, the detectors being at the end of different channels from a particle source and having substantially the same length. The system can include a processor configured to compute a test statistic from the stored measurements. The test statistic may express a Bell inequality, and the system can compare the test statistic with a threshold. The processor can be configured to generate and output a certificate certifying that the measurements are from a quantum system if the value of the computed test statistic passes the threshold.

Techniques facilitating frequency allocation in multi-qubit circuits are provided. In one example, a computer-implemented method comprises determining, by a device operatively coupled to a processor, an estimated fabrication yield associated with respective qubit chip configurations by conducting simulations of the respective qubit chip configurations at respective frequency offsets; and selecting, by the device, a qubit chip configuration from among the respective qubit chip configurations based on the estimated fabrication yield associated with the respective qubit chip configurations.

A novel and useful system and method of generating quantum unitary noise using silicon based quantum dot arrays. Unitary noise is derived from a probability of detecting a particle within a quantum dot array structure comprising position based charge qubits with two time independent basis states |0> and |1>. A two level electron tunneling device such as an interface device, qubit or other quantum structure is used to generate quantum noise. The electron tunneling device includes a reservoir of particles, a quantum dot, and a barrier that is used to control tunneling between the reservoir and the quantum dot. A detector circuit connected to the device outputs a digital stream corresponding to the probability of a particle of being detected. Controlling the bias applied to the barrier controls the probability of detection. Thus, the probability density function (PDF) of the output unitary noise can be controlled to correspond to a desired probability. The unitary noise can be used in stochastic rounding by controlling the bias applied to the barrier in accordance with a remainder of numbers to be rounded.

Provided are various spacecraft propulsion systems, and associated methods of operation. A spacecraft comprises an ion propulsion system and an ion blocker suspended from the spacecraft via one or more electrically insulated tethers. The ion propulsion system is configured to generate a first propulsive force by emitting a charged ion beam in a direction with an ion velocity vector comprising an ion vector component that is perpendicular to a magnetic field of a planet, such as Earth. The magnetic field causes the ion beam to curve toward the ion blocker at a trajectory such that ions within the ion beam are blocked by the ion blocker to generate a second propulsive force on the ion blocker. The ion blocker blocks the ions by contacting or deflecting the ions. The ion blocker is positioned approximately twice the gyroradius of the ion beam trajectory.

A system and method for storing information in a quantum computer using a quantum storage ring. The method comprises cooling ions in the quantum storage ring to a low temperature; and binding the ions into a lattice structure, forming an ion Coulomb crystal.

Described herein are devices incorporating Casimir cavities, which modify the quantum vacuum mode distribution within the cavities. The Casimir cavities can drive charge carriers from or to an electronic device disposed adjacent to or contiguous with the Casimir cavity by modifying the quantum vacuum mode distribution incident on one side of the electronic device to be different from the quantum vacuum mode distribution incident on the other side of the electronic device. The electronic device can exhibit a structure that permits transport or capture of hot carriers in very short time intervals, such as in 1 picosecond or less.

Techniques facilitating formation of amorphous superconducting alloys for superconducting circuits are provided. A device can comprise one or more superconducting components that comprise an amorphous superconducting alloy comprising two or more elements. At least one element of the two or more elements is a superconducting element.

A method for fabricating a single electron transistor is provided. A substrate includes a substantially planar surface with a source electrode, a drain electrode, and a gate electrode thereon, with the source and drain electrodes spaced apart from one another by a gap. The source electrode and the drain electrode are electrified, and a single nanometer-scale conductive particle is electrospray deposited in the gap. The single nanometer-scale conductive particle has an effective size of not greater than 10 nanometers. At least one carbon nanotube is deposited on the substrate and subjected to dielectrophoresis to position the carbon nanotube within 1 nanometer of the single nanometer-scale conductive particle. The at least one carbon nanotube establishes a first connection between the source electrode and the single nanometer-scale conductive particle and a second connection between the drain electrode and the single nanometer-scale conductive particle.