An integrated qubit readout circuit is presented, which includes a superconducting parametric amplifier, a circuit board arranged to mount the superconducting parametric amplifier, a circulator mounted on the circuit board and connected to the superconducting parametric amplifier, wherein the circulator comprises a termination port electrically connected to a termination resistor arranged to terminate a pump tone received by the superconducting parametric amplifier, and wherein the termination resistor is mounted on the circuit board.

A hysteretic magnetic Josephson junction (HMJJ) device is provided that comprises a non-magnetic spacer disposed between a first ferromagnetic layer and a second ferromagnetic layer, a first ferrimagnetic layer having a first side disposed on a side of the first ferromagnetic layer opposite the non-magnetic spacer, and a second ferrimagnetic layer having a first side disposed on a side of the second ferromagnetic layer opposite the non-magnetic spacer. The first ferrimagnetic layer and the second ferrimagnetic layer are formed from a composition that provides orthogonally magnetic responses relative to the magnetic responses of the first ferromagnetic layer and the second ferromagnetic layer. The HMJJ further comprises a first superconducting material layer having a first side disposed on a second side of the first ferromagnetic layer and a second superconducting material layer having a first side disposed on a second side of the second ferromagnetic layer.

A hysteretic magnetic Josephson junction (HMJJ) device is provided that comprises a non-magnetic spacer disposed between a first ferromagnetic layer and a second ferromagnetic layer, a first ferrimagnetic layer having a first side disposed on a side of the first ferromagnetic layer opposite the non-magnetic spacer, and a second ferrimagnetic layer having a first side disposed on a side of the second ferromagnetic layer opposite the non-magnetic spacer. The first ferrimagnetic layer and the second ferrimagnetic layer are formed from a composition that provides orthogonally magnetic responses relative to the magnetic responses of the first ferromagnetic layer and the second ferromagnetic layer. The HMJJ further comprises a first superconducting material layer having a first side disposed on a second side of the first ferromagnetic layer and a second superconducting material layer having a first side disposed on a second side of the second ferromagnetic layer.

Trap circuits for use with superconducting integrated circuits having differential capacitively-coupled resonant clock networks are described. An example superconducting integrated circuit (IC) includes a first superconducting circuit comprising: (1) a first Josephson junction (JJ) coupled via a first capacitor to a first clock line, where the first capacitor is configured to receive a first clock signal having a first phase via the first clock line and couple a first bias current to the first JJ, and (2) a second JJ coupled via a second capacitor to a second clock line, where the second capacitor is configured to receive a second clock signal having a second phase via the second clock line and couple a second bias current to the second JJ. The superconducting IC further includes a first trap circuit for the first superconducting circuit and a second trap circuit for a second superconducting circuit having additional JJs.

Circuits and methods of operation that can facilitate reducing surface losses for quantum devices are provided. In one example, a quantum device can comprise a dielectric layer, a first electrode, and a second electrode. The dielectric layer can comprise a recess formed in a surface of the dielectric layer that reduces a thickness of the dielectric layer from a first thickness external to a footprint of the recess to a second thickness within the footprint of the recess. The second thickness can be less than the first thickness. The first electrode can be positioned within the footprint of the recess. The second electrode can be electrically isolated from the first electrode by the dielectric layer. The first and second electrodes can be positioned on opposing surfaces of the dielectric layer.

Among other things, an apparatus comprises quantum units; and couplers among the quantum units. Each coupler is configured to couple a pair of quantum units according to a quantum Hamiltonian characterizing the quantum units and the couplers. The quantum Hamiltonian includes quantum annealer Hamiltonian and a quantum governor Hamiltonian. The quantum annealer Hamiltonian includes information bearing degrees of freedom. The quantum governor Hamiltonian includes non-information bearing degrees of freedom that are engineered to steer the dissipative dynamics of information bearing degrees of freedom.

Techniques facilitating a quantum gate between qubits using a tunable coupler are provided. In one example, a quantum coupler device can comprise a Josephson ring modulator (JRM) that is operatively coupled to first and second qubits in a balanced bridge topology via respective first and second capacitive devices. The JRM provides tunable coupling between the first and second qubits.

A superconducting circuit includes a first port and a plurality of second ports; a plurality of filter poles, each filter pole comprising an inductor and a capacitor connected in parallel, between the first port and a second port in the plurality of second ports; an admittance inverter comprising at least one of a coupling capacitor, a coupling inductor, and a Josephson junction, the admittance inverter linking two successive filter poles together. The plurality of filter poles and associated admittance inverters define a plurality of current branches so that, when operating as a demultiplexer, an input electrical current input though the first port is routed to a selected one of the plurality of the plurality of second ports by an application of a first set of magnetic flux biases.

A qubit includes a substrate, and a first capacitor structure having a lower portion formed on a surface of the substrate and at least one first raised portion extending above the surface of the substrate. The qubit further includes a second capacitor structure having a lower portion formed on the surface of the substrate and at least one second raised portion extending above the surface of the substrate. The first capacitor structure and the second capacitor structure are formed of a superconducting material. The qubit further includes a junction between the first capacitor structure and the second capacitor structure. The junction is disposed at a predetermined distance from the surface of the substrate and has a first end in contact with the first raised portion and a second end in contact with the second raised portion.

The present invention relates to an inductive dipole element for a superconducting microwave quantum circuit. The dipole element comprises a DC-SQUID formed by a pair of Josephson junctions shunted by an inductance, wherein the Josephson junctions have equal energy, and the Josephson junctions and the inductance are arranged such that each of the junctions forms a loop with the inductance. The two loops are asymmetrically threaded with external magnetic DC fluxes φ.sub.ext1 and φ.sub.ext2, respectively, such that φ.sub.ext1=π and φ.sub.ext2=0, wherein parametric pumping is enabled by modulating the total flux φ.sub.Σ=φ.sub.ext,1+φ.sub.ext,2 threading the dipole element, thereby allowing even-wave mixing between modes that participate in the dipole element with no Kerr-like interactions.