A superconducting memory cell includes a magnetic Josephson junction (MJJ) with a ferromagnetic material, having at least two switchable states of magnetization. The binary state of the MJJ manifests itself as a pulse appearing, or not appearing, on the output. A superconducting memory includes an array of memory cells. Each memory cell includes a comparator with at least one MJJ. Selected X and Y-directional write lines in their combination are capable of switching the magnetization of the MJJ. A superconducting device includes a first and a second junction in a stacked configuration. The first junction has an insulating layer barrier, and the second junction has an insulating layer sandwiched in-between two ferromagnetic layers as barrier. An electrical signal inputted across the first junction is amplified across the second junction.

The present disclosure discloses a device and a method for fabricating a superconducting circuit including a superconducting qubit. The superconducting circuit comprises a bottom electrode interconnecting a superconducting qubit and a first part of the superconducting circuit. The bottom electrode comprises a bottom electrode of the superconducting qubit and a bottom electrode of the first part of the superconducting circuit. The bottom electrode of the superconducting qubit and the bottom electrode of the first part of the superconducting circuit are formed in a first superconducting layer.

A Josephson junction (JJ) device is provided. The JJ device comprises an operating JJ, a first hydrogen-trapping JJ having a first end coupled to a first end of the operating JJ and a second end coupled to a first superconductor wire, and a second hydrogen-trapping JJ having a first end coupled to a second end of the operating JJ and a second end coupled to a second superconductor wire. The first hydrogen-trapping JJ and the second hydrogen-trapping JJ mitigates hydrogen diffusion into the operating JJ.

One example includes a superconducting circuit. The circuit superconducting circuitry fabricated on a first surface of a circuit layer. The circuit layer includes a dielectric material. The circuit also includes a metal layer formed on a second surface of the circuit layer opposite the first surface and a through-substrate via (TSV) conductively coupled to the metal layer and extending through the circuit layer to the first surface. The circuit further includes a flux gasket conductively coupled to and extending from the TSV on the first surface proximal to the superconducting circuitry. The flux gasket can be configured to divert magnetic fields away from the superconducting circuitry.

One example includes a superconducting circuit. The circuit superconducting circuitry fabricated on a first surface of a circuit layer. The circuit layer includes a dielectric material. The circuit also includes a metal layer formed on a second surface of the circuit layer opposite the first surface and a through-substrate via (TSV) conductively coupled to the metal layer and extending through the circuit layer to the first surface. The circuit further includes a flux gasket conductively coupled to and extending from the TSV on the first surface proximal to the superconducting circuitry. The flux gasket can be configured to divert magnetic fields away from the superconducting circuitry.

A superconducting complex quantum computing circuit includes a circuit substrate in which a wiring pattern of a circuit element including quantum bits and measurement electrodes, and ground patterns are formed, and through-electrodes connecting the ground pattern formed on a first surface of the substrate surface and the ground pattern formed on a second surface; a first ground electrode including a first contact portion in contact with the ground patterns, and a first non-contact portion having a shape corresponding to a shape of the wiring pattern; a second ground electrode including a second contact portion in contact with the ground pattern; a control signal line provided with a contact spring pin at a tip; and a pressing member that presses the first ground electrode against the first surface of the circuit substrate or presses the second ground electrode against the second surface of the circuit substrate.

A method of measuring contact resistance at an interface for superconducting circuits is provided. The method includes using a chain structure of superconductors to measure a contact resistance at a contact between contacting superconductor. The method further includes eliminating ohmic resistance from wire lengths in the chain structure by operating below the lowest superconducting transition temperature of all the superconductors in the chain structure. The measurement is dominated by contact resistances of the contacts between contacting superconductors in the chain.

In many cases after degaussing the field distribution in a magnetic material there may be regions within the magnetic material that have ordered domains that contribute a remnant field. There is the need to reduce or eliminate non-uniform fields within a volume of interest left after degaussing a magnetic shield. Degaussing coils surrounding a metal shield can be used to favorably order magnetic domains within the material to counteract the remnant fields left behind following imperfect degaussing. The remnant field value can be measured and a small current may be applied through the degaussing coils. After removing the current, the field can be measured again and a higher current may be applied again through the coils. Repeated applications of currents and field measurement will progressively order domains in the direction of the applied field, resulting in a reduction of the net field and lower field gradient across the volume of interest.

At a first terminal of a structure capable of hosting Majorana Zero Modes, a first set of data points measuring conductance between the first terminal and a middle terminal of the structure is obtained for different values of bias voltage at the first terminal and at least one other parameter. At a second terminal of the structure, a second set of data points measuring conductance between the second terminal and the middle terminal is obtained for different values of bias voltage at the second terminal and of the at least one other parameter. A measure of mutual information is obtained between the first and second data sets. It is determined whether a signature consistent with a pair of Majorana Zero Modes is present in the structure based on the measure of mutual information. The method may be carried out by a quantum computer.

Memory devices and methods are provided. In one aspect, a memory device may comprise a first field element, a second field element, a movable magnetic element, and a first heater. The first field element may be a superconductor. The second field element may be disposed facing the first field element and at a first distance from the first field element. The movable magnetic element may be repelled by the second field element and disposed in a space between the first field element and the second field element. The first heater may be arranged near the first field element. The movable magnetic element may move toward the first field element in response to a first electric current that passes through the first heater.