A quantum processor comprises a plurality of tiles, the plurality of tiles arranged in a first grid, and where a first tile of the plurality of tiles comprises a number of qubits (e.g., superconducting qubits). The quantum processor further comprises a shift register comprising at least one shift register stage communicatively coupled to a frequency-multiplexed resonant (FMR) readout, a qubit readout device, a plurality of digital-to-analog converter (DAC) buffer stages, and a plurality of shift-register-loadable DACs arranged in a second grid. The quantum processor may further include a transmission line comprising at least one transmission line inductance, a superconducting resonator, and a coupling capacitance that communicatively couples the superconducting resonator to the transmission line. A digital processor may program at least one of the plurality of shift-register-loadable DACs. Programming the first tile may be performed in parallel with programming a second tile of the plurality of tiles.

A method for manipulating a group of quantum dots of a quantum dots matrix, called target group, each target group including a quantum dot and containing a charged particle, the matrix being connected to a reservoir of charged particles, each target group being defined by a potential barrier, each charged particle being a carrier of a charge and spin, the method including, for each target group, a total isolation procedure of the target group relative to the other quantum dots, the potential barrier separating the target group of quantum dots of the matrix adjacent to the target group being configured so that the charged particle(s) contained in the target group cannot cross the potential barrier in order to be moved to the adjacent quantum dots or to the reservoir even when such a transition is authorised from an energy standpoint; and maintaining the target group in the completely isolated regime.

Apparatus and methods for real time calibration of qubits in a quantum processor. For example, one embodiment of an apparatus comprises: a quantum processor comprising a plurality of qubits, each of the qubits having a state; a quantum controller to generate sequences of electromagnetic (EM) pulses to manipulate the states of the plurality of qubits based on a set of control parameters; a qubit measurement unit to measure one or more sensors associated with a corresponding one or more of the qubits of the plurality of qubits to produce one or more corresponding measured values; and a machine-learning engine to evaluate the one or more measured values in accordance with a machine-learning process to generate updated control parameters, wherein the quantum controller is to use the updated control parameters to generate subsequent sequences of EM pulses to manipulate the states of the plurality of qubits.

Techniques for creating an offset embedded ground plane cutout for a qubit device to facilitate frequency tuning of the qubit device are presented. A qubit device can comprise a first substrate and second substrate in a flip-chip assembly. The qubit chip assembly can comprise a qubit component fabricated on the first substrate. The qubit component can comprise a Josephson junction (JJ) circuit that can be offset from a center point of the qubit component. The qubit chip assembly can comprise an embedded ground plane situated on a surface of the qubit chip assembly. A cutout section can be formed in the ground plane and positioned over the JJ circuit. The cutout section can enable access of an optical signal or magnetic flux to the JJ circuit. A frequency of the qubit component can be tuned based on application of the optical signal or magnetic flux to the JJ circuit.

A tunable resonator is formed by shunting a set of asymmetric DC-SQUIDs with a capacitive device. An asymmetric DC-SQUID includes a first Josephson junction and a second Josephson junction, where the critical currents of the first and second Josephson junctions are different. A coupling is formed between the tunable resonator and a qubit such that the capacitively-shunted asymmetric DC-SQUIDs can dispersively read a quantum state of the qubit. An external magnetic flux is set to a first value and applied to the tunable resonator. A first value of the external magnetic flux causes the tunable resonator to tune to a first frequency within a first frequency difference from a resonance frequency of the qubit, the tunable resonator tuning to the first frequency causes active reset of the qubit.

A vector signal generator is capable of operating on microwave frequencies. It comprises a microwave resonator, an output for coupling microwave photons out of said microwave resonator, and a Josephson junction or junction array coupled to the microwave resonator for emitting microwave signals into the microwave resonator. A biasing circuit is provided for applying a bias to the Josephson junction or junction array. A tunable attenuator is coupled to said microwave resonator.

A quantum processing unit is disclosed. The quantum processing unit includes at least one superconducting qubit that is based on phase-biased linear and non-linear inductive-energy elements. A superconducting phase difference across the linear and non-linear inductive-energy elements is biased, for example, by an external magnetic field, such that quadratic potential energy terms of the linear and non-linear inductive-energy elements are cancelled at least partly. In a preferred embodiment, such cancellation is at least 30%. The partial cancellation of the quadratic potential energy terms makes it possible to implement a high-coherence high-anharmonicity superconducting qubit design.

Described herein are structures that include flux bias lines for controlling frequencies of qubits in quantum circuits. An exemplary structure includes a substrate, a qubit provided over a surface of the substrate, and a flux bias line provided below the surface of the substrate and configured to control the frequency of the qubit via a magnetic field generated as a result of a current flowing through the flux bias line. Methods for fabricating such structures are disclosed as well.

A quantum bit device according to the present invention includes a first quantum bit substrate 10 which includes a first superconductive wiring 13 disposed to have a magnetically coupled portion with a first superconductive magnetic flux quantum bit 14 on a surface thereof, a second quantum bit substrate 11 which includes a second superconductive wiring 13 disposed to have a magnetically coupled portion with a second superconductive magnetic flux quantum bit 14 on a surface thereof, and a base substrate 12 which includes a third superconductive wiring 13 configured by two superconductive wirings extending parallel to each other on a surface thereof. The first and second quantum bit substrates are placed on the base substrate, two end portions of the first superconductive wiring and two end portions on one side of the third superconductive wiring are joined via superconductive solders 15, two end portions of the second superconductive wiring and two end portions on the other side of the third superconductive wiring are joined via superconductive solders 15, and three of the first to third superconductive wirings form one continuous superconductive loop.

This disclosure relates to optical devices for quantum information processing applications. In one example implementation, a semiconductor structure is provided. The semiconductor structure may be embedded with single defects that can be individually addressed. An electric bias and/or one or more optical excitations may be configured to control the single defects in the semiconductor structure to produce single photons for use in quantum information processing. The electric bias and optical excitations are selected and adjusted to control various carrier processes and to reduce environmental charge instability of the single defects to achieve optical emission with wide wavelength tunability and narrow spectral linewidth. Electrically controlled single photon source and other electro-optical devices may be achieved.