Abstract: Method of making a low resistivity electrical connection between an electrical conductor and an iron pnictide superconductor involves connecting the electrical conductor and superconductor using a tin or tin-based material therebetween, such as using a tin or tin-based solder. The superconductor can be based on doped AFe2As2, where A can be Ca, Sr, Ba, Eu or combinations thereof for purposes of illustration only.

Abstract: Superconducting integrated circuits require several wiring layers to distribute bias and signals across the circuit, which must cross each other both with and without contacts. All wiring lines and contacts must be fully superconducting, and in the prior art each wiring layer comprises a single metallic thin film. An alternative wiring layer is disclosed that comprises sequential layers of two or more different metals. Such a multi-metallic wiring layer may offer improved resistance to impurity diffusion, better surface passivation, and/or reduction of stress, beyond that which is attainable with a single-metallic wiring layer. The resulting process leads to improved margin and yield in an integrated circuit comprising a plurality of Josephson junctions. Several preferred embodiments are disclosed, for both planarized and non-planarized processes.

Abstract: A three-port component comprises a source electrode, a drain electrode, and a channel, which is corrected between the source electrode and the drain electrode and which is made of a material haying an electronic conductivity that can be varied by supplying and/or removing ions. The three-port component comprises an ion reservoir, which is in contact with a gate electrode, and which is connected to the channel so that the reservoir is able to exchange ions with the channel when a potential is applied to the gate electrode. Information can be stored on the three-port component by distributing the total number of ions, which are present in the ion reservoir and the channel, between the ion reservoir and the channel. The distribution of ions in the channel and the ion reservoir changes when, and only when, a corresponding driving potential is applied to the gate electrode. Thus, in contrast to RRAMS, there is no time-voltage dilemma.

Abstract: A superconducting circuit, and a method, are disclosed for generating pulses with stable frequency. The circuit includes an annular Long Josephson Junction (LJJ) capable of producing electrical pulses of a desired frequency due to a steady bias current applied to the LJJ. The circuit further includes an electrical interface for injecting an RF signal of a first frequency into the annular LJJ, resulting in the desired frequency locking onto the first frequency. Typically the first frequency substantially equals the desired frequency. The injection of the RF signal further results in the decrease of the frequency jitter of the desired frequency. The pulses generated in the loop section of the LJJ are outputted through a tail section of the LJJ, and through transmission lines which couple to the tail section.

Abstract: A superconducting multi-bit digital mixer, designed using rapid single flux quantum (RSFQ) logic, for multiplying two independent digital streams, at least one of these comprising a plurality of parallel bit lines, wherein the output is also a similar plurality of bit lines. In a preferred embodiment, one of the digital streams represents a local oscillator signal, and the other digital stream digital radio frequency input from an analog-to-digital converter. The multi-bit mixer comprises an array of bit-slices, with the local oscillator signal generated using shift registers. This multi-bit mixer is suitable for an integrated circuit with application to a broadband digital radio frequency receiver, a digital correlation receiver, or a digital radio frequency transmitter. A synchronous pulse distribution network is used to ensure proper operation at data rates of 20 GHz or above.

Abstract: A reciprocal quantum logic (RQL) latch system is provided. The latch system comprises an output portion that retains a state of the latch system, and a bi-stable loop that comprises a set input, a reset input and an output coupled to the output portion. A positive single flux quantum (SFQ) pulse on the set input when the latch system is in a reset state results in providing a SFQ current in the output portion representative of the latch system being in a set state.

Abstract: New type of Josephson switch based on Josephson superconductor/insulator/ferromagnet/superconductor (SIFS) junction is disclosed. This Josephson SIFS junction has a ferromagnetic (F-) barrier whose magnetization can be controlled by magnetic field pulses. The critical current of such SIFS junction can be controlled using the remanent magnetization of the junction ferromagnetic (F-) barrier. The proposed switch exploits a weakly ferromagnetic (F-) thin-film inner layer with in-plane magnetic anisotropy and small coercive field (for example, Pd0.99Fe0.01-thin-film barrier). A Nb—Pd0.99Fe0.01—Nb SFS sandwich can be switched between two states of Jesephson critical currents or between zero-resistance and resistive states by magnetic field pulses. It is important that the critical current states remain unchanged for a sufficient length of time at low temperatures without any applied magnetic field.

Abstract: In a cold superconducting joint, a joint cup is provided. Lengths of superconducting filaments are placed in the joint cup. A superconducting material fills the joint cup in contact with the superconducting filaments and in thermal and mechanical contact with a pipe carrying a cryogen. The pipe extends into the joint cup and the superconducting material extends around the pipe within the joint cup.

Abstract: A superconducting cable terminal connection device connecting a terminal of a superconducting cable for power transmission to an external power system, includes: an electric field relaxation shield disposed inside an insulation housing; a horizontal conductor fixed to an end portion of a core of the superconducting cable drawn into the electric field relaxation shield; an insulator which coats an outer periphery of the horizontal conductor; a vertical conductor which is drawn into the electric field relaxation shield and has a through-hole through which the horizontal conductor and the insulator pass so as to be slidable in a lengthwise direction; and a flexible electrical conduction member which electrically connects an end portion of the horizontal conductor to the vertical conductor.

Abstract: Superconducting integrated circuits require several wiring layers to distribute bias and signals across the circuit, which must cross each other both with and without contacts. All wiring lines and contacts must be fully superconducting, and in the prior art each wiring layer comprises a single metallic thin film. An alternative wiring layer is disclosed that comprises sequential layers of two or more different metals. Such a multi-metallic wiring layer may offer improved resistance to impurity diffusion, better surface passivation, and/or reduction of stress, beyond that which is attainable with a single-metallic wiring layer. The resulting process leads to improved margin and yield in an integrated circuit comprising a plurality of Josephson junctions. Several preferred embodiments are disclosed, for both planarized and non-planarized processes.

Abstract: A terminal apparatus for a superconducting cable system connects an overhead transmission cable or power appliance such as a breaker in an ambient temperature state to a superconducting cable through which power is transmitted at a cryogenic temperature. The terminal apparatus has: a refrigerant tub which is connected to the end of a superconducting cable and is filled with a refrigerant; a vacuum heat insulating container that surrounds the exterior of the refrigerant tub; a current lead having one end connected to the end portion of the superconducting cable and the other end connected to the overhead transmission cable or power appliance through the refrigerant tub and the vacuum heat insulating container; and a superconducting fault current limiter installed at a center portion of the current lead in the interior of the refrigerant tub to limit fault current.

Abstract: A twisted track interferometer (TTI) for producing magic states is disclosed. The spin of ½-vortices may be exploited to produce magic states. The disclosed “twisted track interferometer” is a “topological twist” on the conventional Pabre-Pero interferometer adapted to topological superconductors. In the disclosed TTI, the probe particles may be Josephson vortices (JVs). JVs are estimated to be light and will tunnel more easily than Abrikosov vortices. Also, the disclosed TTI does not require multiple tunneling events. Rather, the JVs are propelled down thin insulating tracks within a 2D topological p-wave superconductor by a Magnus force generated by a tunneling supercurrent across the tracks. The JVs encounter tunneling junctions as they pass into the arms of the TTI.

Abstract: A superconducting circuit, and a method, are disclosed for generating pulses with stable frequency. The circuit includes an annular Long Josephson Junction (LJJ) capable of producing electrical pulses of a desired frequency due to a steady bias current applied to the LJJ. The circuit further includes an electrical interface for injecting an RF signal of a first frequency into the annular LJJ, resulting in the desired frequency locking onto the first frequency. Typically the first frequency substantially equals the desired frequency. The injection of the RF signal further results in the decrease of the frequency jitter of the desired frequency. The pulses generated in the loop section of the LJJ are outputted through a tail section of the LJJ, and through transmission lines which couple to the tail section.

Abstract: A novel Josephson junction and a novel Josephson junction device are provided which eliminates the need to form an insulating barrier layer. The Josephson junction (1) comprises a superconductor layer (2) and a ferromagnetic layer (3) formed on a middle part (2C) of the superconductor layer (2). The ferromagnetic layer (3) may consist of an electrically conductive or insulating ferromagnetic layer, and may be an electrically conductive ferromagnetic layer formed via an insulating layer. With the superconductor layer (2) formed of a high temperature superconductor, a Josephson junction (1) is provided having large IcRN product. The Josephson junction (1) can be used as a junction for a variety of Josephson devices.

Abstract: The present invention provides a superconducting device including a substrate, a first superconducting pattern formed on the substrate, an insulating pattern formed on the first superconducting pattern, and a second superconducting pattern formed at the uppermost level in the multilayered superconducting pattern. A barrier layer of a Josephson junction is formed on the lower side of, or within the second superconducting pattern. The second superconducting pattern constitutes a circuit element on the insulating pattern.

Abstract: A new family of superconducting materials with critical temperature up to 55 K have recently been discovered, comprising a crystal structure with atomic layers of iron and arsenic alternating with atomic layers of rare-earth oxide or alkaline earth. The present invention identifies structures for integrated circuit elements (including Josephson junctions) in these and related materials. These superconducting circuit elements will operate at a higher temperature than low-temperature superconductors such as niobium, and may be easier to manufacture than prior-art high-temperature superconductors based on copper-oxides.

Abstract: A Josephson device includes a first superconducting electrode layer, a barrier layer and a second superconducting electrode layer that are successively stacked. The first and second superconducting electrode layers are made of an oxide superconductor material having (RE)1(AE)2Cu3Oy as a main component, where an element RE is at least one element selected from a group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, and an element AE is at least one element selected from a group consisting of Ba, Sr and Ca. The barrier layer is made of a material that includes the element RE, the element AE, Cu and oxygen, where in cations within the material forming the barrier layer, a Cu content is in a range of 35 At. % to 55 At. % and an RE content is in a range of 12 At. % to 30 At. %, and the barrier layer has a composition different from compositions of the first and second superconducting electrode layers.

Abstract: A superconducting integrated circuit may include a magnetic flux transformer having an inner inductive coupling element and an outer inductive coupling element that surrounds the inner inductive coupling element along at least a portion of a length thereof. The magnetic flux transformer may have a coaxial-like geometry such that a mutual inductance between the first inductive coupling element and the second inductive coupling element is sub-linearly proportional to a distance that separates the first inner inductive coupling element from the first outer inductive coupling element. At least one of the first inductive coupling element and the second inductive coupling element may be coupled to a superconducting programmable device, such as a superconducting qubit.

Abstract: It is possible to improve the negative resistance characteristic that can be expected when an SNS (superconductor-normal conductor-superconductor) structure is used as a structure unit for series connection. On the top of a first superconducting electrode, a second superconducting electrode is superimposed so as to sandwich an insulation film between the first and second superconducting electrodes, with parts of cross sections of the second superconducting electrode and insulation film placed on the top. A normal superconducting line electrically connects the first and second superconducting electrodes passing along the cross section of the insulation film, thereby constituting a structure unit having a single weak link. A plurality of such structure units connected in series are prepared. At the both ends of the series the first or second superconducting electrode is an element connected to a leading line.

Abstract: The invention relates to a coil for producing a magnetic field having at least one winding (12), which is manufactured from a superconductor, is cast into a plastic and whose winding end (19) which is arranged at the circumference (13) of the winding (12) is used for making contact with an electrical conductor (15). In order to provide coils with windings (12) consisting of superconductors which make robust contact-making possible given simple production, an electrically conductive connection piece (30) with a base region (31), which is connected to the winding end (19), and a top region (32) for connecting the conductor (15) is provided for contact-making purposes, the base region (31) of said connection piece (30) being covered partially in the radial direction by a reinforcing insert (14), which is cast into the plastic (20) and at least partially surrounds the winding (12).

Abstract: A Josephson junction (JJ) device includes a buffered substrate comprising a first buffer layer formed on a substrate. A second buffer layer is formed on the first buffer layer. The second buffer layer includes a hexagonal compound structure. A trilayer structure is formed on the buffered substrate comprising at least two layers of a superconducting material. A thin tunnel barrier layer is positioned between the at least two layers. The buffered substrate is used to minimize lattice mismatch and interdiffusion in the trilayer structure so as to allow the JJ device to operate above 20 K.

Abstract: A compact, solid-state THz source based on the driven Josephson vortex lattice in a highly anisotropic superconductor such as Bi2Sr2CaCu2O8 that allows cw emission at tunable frequency. A second order metallic Bragg grating is used to achieve impedance matching and to induce surface emission of THz-radiation from a Bi2Sr2CaCu2O8 sample. Steering of the emitted THz beam is accomplished by tuning the Josephson vortex spacing around the grating period using a superimposed magnetic control field.

Abstract: A compact, solid-state THz source based on the driven Josephson vortex lattice in a highly anisotropic superconductor such as Bi2Sr2CaCu2O8 that allows cw emission at tunable frequency. A second order metallic Bragg grating is used to achieve impedance matching and to induce surface emission of THz-radiation from a Bi2Sr2CaCu2O8 sample. Steering of the emitted THz beam is accomplished by tuning the Josephson vortex spacing around the grating period using a superimposed magnetic control field.

Abstract: A compact, solid-state THz source based on the driven Josephson vortex lattice in a highly anisotropic superconductor such as Bi2Sr2CaCu2O8 that allows cw emission at tunable frequency. A second order metallic Bragg grating is used to achieve impedance matching and to induce surface emission of THz-radiation from a Bi2Sr2CaCu2O8 sample. Steering of the emitted THz beam is accomplished by tuning the Josephson vortex spacing around the grating period using a superimposed magnetic control field.

Abstract: A Josephson junction (JJ) device includes a buffered substrate comprising a first buffer layer formed on a substrate. A second buffer layer is formed on the first buffer layer. The second buffer layer includes a hexagonal compound structure. A trilayer structure is formed on the buffered substrate comprising at least two layers of a superconducting material. A thin tunnel barrier layer is positioned between the at least two layers. The buffered substrate is used to minimize lattice mismatch and interdiffusion in the trilayer structure so as to allow the JJ device to operate above 20 K.

Abstract: In one embodiment, the invention is a hybrid superconducting-magnetic memory cell and array. One embodiment of a memory cell includes a magnetoresistive element and at least one superconducting element wired in parallel with the magnetoresistive element. In a further embodiment, memory cells of the disclosed configuration are arranged to form a memory array.

Abstract: A novel Josephson junction and a novel Josephson junction device are provided which eliminates the need to form an insulating barrier layer. The Josephson junction (1) comprises a superconductor layer (2) and a ferromagnetic layer (3) formed on a middle part (2C) of the superconductor layer (2). The ferromagnetic layer (3) may consist of an electrically conductive or insulating ferromagnetic layer, and may be an electrically conductive ferromagnetic layer formed via an insulating layer. With the superconductor layer (2) formed of a high temperature superconductor, a Josephson junction (1) is provided having large IcRN product. The Josephson junction (1) can be used as a junction for a variety of Josephson devices.

Abstract: A Bi-based oxide superconductor thin film whose c-axis is oriented parallel to the substrate and whose a-axis (or b-axis) is oriented perpendicular to the substrate, is manufactured in order to obtain a high performance layered Josephson junction using a Bi-based oxide superconductor. The method of manufacturing an a-axis oriented Bi-based oxide superconductor thin film, involves an epitaxial growth process using an LaSrAlO4 single crystal substrate of a (110) plane or a LaSrGaO4 single crystal substrate of a (110) plane, for which the lattice constant matches well with a (100) plane of a Bi-2223 oxide superconductor. By this method, rather than the normally easily obtained Bi-2212, an a-axis oriented film of Bi-2223 showing an extremely high superconductive transition temperature even for a Bi-based oxide superconductor can be selectively manufactured.

Abstract: A system employs a plurality of physical qubits, each having a respective bias operable to up to six differentiable inputs to solve a Quadratic Unconstrained Binary Optimization problem. Some physical qubit couplers are operated as intra-logical qubit couplers to ferromagnetically couple respective pairs of the physical qubits as a logical qubit, where each logical qubit represents a variable from the Quadratic Unconstrained Binary Optimization problem.

Abstract: A superconducting flux digital-to-analog converter includes a superconducting inductor ladder circuit. The ladder circuit includes a plurality of closed superconducting current paths that each includes at least two superconducting inductors coupled in series to form a respective superconducting loop, successively adjacent or neighboring superconducting loops are connected in parallel with each other and share at least one of the superconducting inductors to form a flux divider network. A data signal input structure provides a respective bit of a multiple bit signal to each of the superconducting loops. The data signal input structure may include a set of superconducting quantum interference devices (SQUIDs). The data signal input structure may include a superconducting shift register, for example a single-flux quantum (SFQ) shift register or a flux-based superconducting shift register comprising a number of latching qubits.

Abstract: A coupling system to couple a first and a second qubit in response to a state of the coupling system that may be set by two input signals.

Abstract: A method of making a superconductor device is described.

Abstract: A Josephson device includes a first superconducting electrode layer, a barrier layer and a second superconducting electrode layer that are successively stacked. The first and second superconducting electrode layers are made of an oxide superconductor material having (RE)1(AE)2Cu3Oy as a main component, where an element RE is at least one element selected from a group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, and an element AE is at least one element selected from a group consisting of Ba, Sr and Ca. The barrier layer is made of a material that includes the element RE, the element AE, Cu and oxygen, where in cations within the material forming the barrier layer, a Cu content is in a range of 35 At. % to 55 At. % and an RE content is in a range of 12 At. % to 30 At. %, and the barrier layer has a composition different from compositions of the first and second superconducting electrode layers.

Abstract: Rare earth metal containing compounds of the formula Sr2YbSbO6 have been prepared with high critical temperature thin film superconductor structures, and can be fabricated into a superconductor insulator superconductor step edge Josephson junction, as well as being used in other ferroelectrics, pyroelectrics, and hybrid device structures.

Abstract: A Superconducting Quantum Interference Device (SQUID) is disclosed comprising a pair of resistively shunted Josephson junctions connected in parallel within a superconducting loop and biased by an external direct current (dc) source. The SQUID comprises a semiconductor substrate and at least one superconducting layer. The metal layer(s) are separated by or covered with a semiconductor material layer having the properties of a conductor at room temperature and the properties of an insulator at operating temperatures (generally less than 100 Kelvins). The properties of the semiconductor material layer greatly reduces the risk of electrostatic discharge that can damage the device during normal handling of the device at room temperature, while still providing the insulating properties desired to allow normal functioning of the device at its operating temperature. A method of manufacturing the SQUID device is also disclosed.

Abstract: This invention relates to an electronic element having an electron function which acts even at room temperature using a super dielectric effect. The element has a crystalline electron system, and uses a perovskite crystal in the ground state of a “macroscopic quantum effect” which occurs when the electron number is defined, or nearly defined. The electronic element used in an electric field such that the two-dimensional plane of doped crystals ground state of a “fractional quantum Hall effect” wherein the doping amount of the crystals is 0.05 or less, or if localization is introduced, 0.6 or less, and the crystals may have a doping amount variation determined by the degree of localization.

Abstract: A method for performing a single-qubit gate on an arbitrary quantum state. An ancillary qubit is set to an initial state |I>. The data qubit is coupled to an ancillary qubit. The state of the ancillary qubit is measured, and the data qubit and the ancillary qubit are coupled for a first period of time. A method for applying a single-qubit gate to an arbitrary quantum state. A state of a first and second ancillary qubit are set to an entangled initial state |I>. A state of a data qubit and the first ancillary qubit are measured thereby potentially performing a single qubit operation on the arbitrary quantum state. A first result is determined. The first result indicates whether the single qubit operation applied the single qubit gate to the arbitrary quantum state.

Abstract: A solid-state quantum computing structure includes a d-wave superconductor in sets of islands that clean Josephson junctions separate from a first superconducting bank. The d-wave superconductor causes the ground state for the supercurrent at each junction to be doubly degenerate, with two supercurrent ground states having distinct magnetic moments. These quantum states of the supercurrents at the junctions create qubits for quantum computing. The quantum states can be uniformly initialized from the bank, and the crystal orientations of the islands relative to the bank influence the initial quantum state and tunneling probabilities between the ground states. A second bank, which a Josephson junction separates from the first bank, can be coupled to the islands through single electron transistors for selectably initializing one or more of the supercurrents in a different quantum state. Single electron transistors can also be used between the islands to control entanglements while the quantum states evolve.

Abstract: A Josephson junction having a barrier layer sandwiched by two superconductors wherein the superconductors include one or more elements selected from the group of Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, one or more elements selected from the group of Ba, Sr and Ca, and Cu and oxygen, wherein the two superconductors each include at least five elements with compositions different from each other, or the barrier layer (5) includes one or more elements selected from the group of La, Nd, Sm and Eu, and one or more elements selected from the group of Y, Gd, Dy, Ho, Er, Tm, Yb and Lu.

Abstract: A qubit (quantum bit) circuit includes a superconducting main loop that is electrically-completed by a serially-interconnected superconducting subloop. The subloop includes two Josephson junctions. A first coil provides a first flux that couples with the main loop but not with the subloop. A second coil provides a second flux that couples with the subloop but not with the main loop.

Abstract: A mesa-shaped superconducting-superlattice structure is formed and adhered with epoxy onto a dielectric substrate where plural superconducting layers and plural insulating layers are naturally and alternately stacked. A ?/4 micro strip line (which means the length of the strip line is one-fourth of the wavelength of a microwave to be introduced) is electrically connected via a metallic film onto the mesa structural portion of the superconducting-superlattice structure, and a metallic electrode is electrically connected to the additional mesa structural portion of the superconducting-superlattice structure via a metallic film.

Abstract: A method of forming a novel high temperature superconducting Josephson junction which is capable of achieving a formation of a Josephson junction having high characteristics conveniently and quickly without necessitating costly micromachining facilities. Two high temperature superconducting whisker crystals are crossed with each other on a substrate and subjected to thermal treatment to form a Josephson junction between the two high temperature superconducting whisker crystals.

Abstract: An optic superconducting circuit element (10) is disclosed that is operable to transmit and receive on an identical chip an electromagnetic wave having frequencies in an extended frequency band ranging from microwave to THz frequency bands and with high sensitivity. The optic superconducting circuit element (10) includes the chip (3), and a superconducting electromagnetic wave oscillating (generating and transmitting) source (16) and a superconducting Josephson junction device (14) disposed in close vicinity to each other on the chip (3), the superconducting Josephson junction device (14) detecting the electromagnetic wave transmitted from the superconducting electromagnetic wave oscillating (generating and transmitting) source (16).

Abstract: In one embodiment, a two-junction phase qubit includes a superconducting loop and two Josephson junctions separated by a mesoscopic island on one side and a bulk loop on another side. The material forming the superconducting loop is a superconducting material with an order parameter that violates time reversal symmetry. In one embodiment, a two-junction phase qubit includes a loop of superconducting material, the loop having a bulk portion and a mesoscopic island portion. The loop further includes a relatively small gap located in the bulk portion. The loop further includes a first Josephson junction and a second Josephson junction separating the bulk portion from the mesoscopic island portion. The superconducting material on at least one side of the first and second Josephson junctions has an order parameter having a non-zero angular momentum in its pairing symmetry. In one embodiment, a qubit includes a superconducting loop having a bulk loop portion and a mesoscopic island portion.

Abstract: A control system for an array of qubits is disclosed. The control system according to the present invention provides currents and voltages to qubits in the array of qubits in order to perform functions on the qubit. The functions that the control system can perform include read out, initialization, and entanglement. The state of a qubit can be determined by grounding the qubit, applying a current across the qubit, measuring the resulting potential drop across the qubit, and interpreting the potential drop as a state of the qubit. A qubit can be initialized by grounding the qubit and applying a current across the qubit in a selected direction for a time sufficient that the quantum state of the qubit can relax into the selected state. In some embodiments, the qubit can be initialized by grounding the qubit and applying a current across the qubit in a selected direction and then ramping the current to zero in order that the state of the qubit relaxes into the selected state.

Abstract: A Josephson junction has inherent resistance which effectively shunts the junction and thereby obviates a separate shunt resistor and thus reduces surface area in an integrated circuit including a plurality of Josephson junctions. The Josephson junction comprises a stacked array of layers of Nb and a superconductor with Tc>9° K having a penetration depth greater than that of Nb, for example NbyTil-yN, with a layer of a conducting material having a resistivity between 200 &mgr;&OHgr;-cm, 1 &OHgr;-cm, such as TaxN in the stack. The Josephson junction can be formed on a supporting substrate such as silicon with a ground plane such as Nb on the substrate and an insulating layer such as SiO2 separating the ground plane from the stacked array.

Abstract: A circuit comprising a superconducting qubit and a resonant control system that is characterized by a resonant frequency. The resonant frequency of the control system is a function of a bias current. The circuit further includes a superconducting mechanism having a capacitance or inductance. The superconducting mechanism coherently couples the superconducting qubit to the resonant control system. A method for entangling a quantum state of a first qubit with the quantum state of a second qubit. In the method, a resonant control system, which is capacitively coupled to the first and second qubit, is tuned to a first frequency that corresponds to the energy differential between the lowest two potential energy levels of the first qubit. The resonant control system is then adjusted to a second frequency corresponding to energy differential between the lowest two potential energy levels of the second qubit.

Abstract: There is provided a superconducting device including a substrate, a first superconductor layer supported by the substrate and containing Ln, AE, M and O, and a second superconductor layer containing a material represented by a formula of (Yb1−yLn′y)AE′2M′3Oz, the first and second superconductor layers forming a junction, and atomic planes each including M and O in the first superconductor layer and atomic planes each including M′ and O in the second superconductor layer being discontinuous to each other in a position of the junction, wherein each of Ln and Ln′ represents at least one metal of Y and lanthanoids, each of AE and AE′ represents at least one of alkaline earth metals, each of M and M′ represents a metal which contains 80 atomic % or more of Cu, y represents a value between 0 and 0.9, and z represents a value between 6.0 and 8.0.

Abstract: A method and structure for a d-wave qubit structure includes a qubit disk formed at a multi-crystal junction (or qubit ring) and a superconducting screening structure surrounding the qubit. The structure may also include a superconducting sensing loop, where the superconducting sensing loop comprises an s-wave superconducting ring. The structure may also include a superconducting field effect transistor.

Abstract: A method of forming a novel high temperature superconducting Josephson junction which is capable of achieving a formation of a Josephson junction having high characteristics conveniently and quickly without necessitating costly micromachining facilities. Two high temperature superconducting whisker crystals are crossed with each other on a substrate and subjected to thermal treatment to form a Josephson junction between the two high temperature superconducting whisker crystals.