Abstract: A method for fabricating a closed-form Josephson junction includes etching the inner shape of the closed-form junction on the chip, depositing a negative photoresist material over the etched chip, and flood exposing the backside of the chip with ultraviolet radiation. The photoresist is developed and then baked onto the chip. The baked photoresist serves as a mask for subsequent etching of the exterior of the closed-form Josephson junction. A shaped Josephson junction is fabricated with junction widths between about 0.1 &mgr;m and about 1 &mgr;m and an inner diameter ranging between about 1 &mgr;m and about 1000 &mgr;m.

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: A system and method for controlling an information state of a superconducting qubit having a superconducting loop that includes a bulk loop portion, a mesoscopic island portion, and two Josephson junctions separating the bulk loop portion from the mesoscopic island portion is described. The method includes applying a bias across the mesoscopic island portion. In one embodiment, the method includes driving a bias current in the superconducting loop. In one embodiment, the method includes driving a bias current in the superconducting loop by coupling a magnetic flux into the superconducting loop. In one embodiment, the control system includes a tank circuit inductively coupled to the superconducting loop. In one embodiment, entanglement between qubits is provided by connections between qubits to be entangled.

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 superconducting structure that includes a mesoscopic phase device and a mesoscopic charge device. The superconducting structure further includes a mechanism for coupling the mesoscopic phase device and the mesoscopic charge device so that the quantum state of the mesoscopic phase device and the quantum state of the mesoscopic charge device interact. In another aspect, the superconducting structure includes a mechanism for reading out the quantum state of the mesoscopic charge device.

Abstract: A solid state dc-SQUID includes a superconducting loop containing a plurality of Josephson junctions, wherein an intrinsic phase shift is accumulated through the loop. In an embodiment of the invention, the current-phase response of the dc-SQUID sits in a linear regime where directional sensitivity to flux through the loop occurs. Changes in the flux passing through the superconducting loop stimulates current which can be quantified, thus providing a means of measuring the magnetic field. Given the linear and directional response regime of the embodied device, an inherent current to phase sensitivity is achieved that would otherwise be unobtainable in common dc-SQUID devices without extrinsic intervention.

Abstract: A method for reading out the state of a mesoscopic phase device. In the method the mesoscopic phase device is coherently coupled to a mesoscopic charge device using a phase shift device and the quantum state of the mesoscopic charge device is measured. A method for reading out the quantum state of a qubit in a heterogeneous quantum register. The heterogeneous quantum register includes a first plurality of phase qubits and a second plurality of charge qubits. In the method a first phase qubit or a first charge qubit in the heterogeneous quantum register is selected. The first phase qubit or the first charge qubit is coherently connected to a mesoscopic charge device for a duration tc. The quantum state of the mesoscopic charge device is read out after the duration tc has elapsed.

Abstract: A superconducting structure that includes a mesoscopic phase device and a mesoscopic charge device. The superconducting structure further includes a mechanism for coupling the mesoscopic phase device and the mesoscopic charge device so that the quantum state of the mesoscopic phase device and the quantum state of the mesoscopic charge device interact. In another aspect, the superconducting structure includes a mechanism for reading out the quantum state of the mesoscopic charge device.

Abstract: A computer program product for use in conjunction with a computer system, the computer program product comprising a computer readable storage medium and a computer program mechanism embedded therein. The computer program mechanism comprises a quantum computing integrated development environment (QC-IDE) module and a compiler module. The QC-IDE module is used to design a quantum logic for a plurality of qubits. The QC-IDE module includes instructions for generating a time resolved set of operators. The compiler module includes instructions for compiling the time resolved set of operators into a set of quantum machine language instructions.

Abstract: A finger SQUID qubit device and method for performing quantum computation with said device is disclosed. A finger SQUID qubit device includes a superconducting loop and one or more superconducting fingers, wherein the fingers extend to the interior of said loop. Each finger has a mesoscopic island at the tip, separated from the rest of the finger by a Josephson junction. A system for performing quantum computation with the finger SQUID qubit device includes a mechanism for initializing, entangling, and reading out the qubits. The mechanism may involve passing a bias current across the leads of the superconducting loop and a mechanism for measuring a potential change across the leads of the superconducting loop. Furthermore, a control system includes a mechanism for addressing specific qubits in a quantum register of finger SQUID devices.

Abstract: A method for performing a quantum computing entanglement operation between a phase qubit and a charge qubit. A coherent connection between the phase qubit and the charge qubit is provided. The coherent connection allows the quantum state of the phase qubit and the quantum state of the charge qubit to interact with each other. The coherent connection is modulated for a duration te. The phase qubit is connected to the charge qubit during at least a portion of the duration te in order to controllably entangle the quantum state of the phase qubit and the quantum state of the charge qubit.

Abstract: A finger SQUID qubit device and method for performing quantum computation with said device is disclosed. A finger SQUID qubit device includes a superconducting loop and one or more superconducting fingers, wherein the fingers extend to the interior of said loop. Each finger has a mesoscopic island at the tip, separated from the rest of the finger by a Josephson junction. A system for performing quantum computation with the finger SQUID qubit device includes a mechanism for initializing, entangling, and reading out the qubits. The mechanism may involve passing a bias current across the leads of the superconducting loop and a mechanism for measuring a potential change across the leads of the superconducting loop. Furthermore, a control system includes a mechanism for addressing specific qubits in a quantum register of finger SQUID devices.

Abstract: A finger SQUID qubit device and method for performing quantum computation with said device is disclosed. A finger SQUID qubit device includes a superconducting loop and one or more superconducting fingers, wherein the fingers extend to the interior of said loop. Each finger has a mesoscopic island at the tip, separated from the rest of the finger by a Josephson junction. A system for performing quantum computation with the finger SQUID qubit device includes a mechanism for initializing, entangling, and reading out the qubits. The mechanism may involve passing a bias current across the leads of the superconducting loop and a mechanism for measuring a potential change across the leads of the superconducting loop. Furthermore, a control system includes a mechanism for addressing specific qubits in a quantum register of finger SQUID devices.

Abstract: A quantum integrated development environment is provided for designing quantum logic that utilizes N qubits, compiling the quantum logic into quantum machine language instructions, and running the machine language instructions on a quantum computing system. Additionally, the results of the execution are provided as an output.

Abstract: A finger SQUID qubit device and method for performing quantum computation with said device is disclosed. A finger SQUID qubit device includes a superconducting loop and one or more superconducting fingers, wherein the fingers extend to the interior of said loop. Each finger has a mesoscopic island at the tip, separated from the rest of the finger by a Josephson junction. A system for performing quantum computation with the finger SQUID qubit device includes a mechanism for initializing, entangling, and reading out the qubits. The mechanism may involve passing a bias current across the leads of the superconducting loop and a mechanism for measuring a potential change across the leads of the superconducting loop. Furthermore, a control system includes a mechanism for addressing specific qubits in a quantum register of finger SQUID devices.

Abstract: A finger SQUID qubit device and method for performing quantum computation with said device is disclosed. A finger SQUID qubit device includes a superconducting loop and one or more superconducting fingers, wherein the fingers extend to the interior of said loop. Each finger has a mesoscopic island at the tip, separated from the rest of the finger by a Josephson junction. A system for performing quantum computation with the finger SQUID qubit device includes a mechanism for initializing, entangling, and reading out the qubits. The mechanism may involve passing a bias current across the leads of the superconducting loop and a mechanism for measuring a potential change across the leads of the superconducting loop. Furthermore, a control system includes a mechanism for addressing specific qubits in a quantum register of finger SQUID devices.

Abstract: Quantum computing systems and methods that use opposite magnetic moment states read the state of a qubit by applying current through the qubit and measuring a Hall effect voltage across the width of the current. For reading, the qubit is grounded to freeze the magnetic moment state, and the applied current is limited to pulses incapable of flipping the magnetic moment. Measurement of the Hall effect voltage can be achieved with an electrode system that is capacitively coupled to the qubit. An insulator or tunnel barrier isolates the electrode system from the qubit during quantum computing. The electrode system can include a pair of electrodes for each qubit. A readout control system uses a voltmeter or other measurement device that connects to the electrode system, a current source, and grounding circuits. For a multi-qubit system, selection logic can select which qubit or qubits are read.

Abstract: Quantum computing systems and methods that use opposite magnetic moment states read the state of a qubit by applying current through the qubit and measuring a Hall effect voltage across the width of the current. For reading, the qubit is grounded to freeze the magnetic moment state, and the applied current is limited to pulses incapable of flipping the magnetic moment. Measurement of the Hall effect voltage can be achieved with an electrode system that is capacitively coupled to the qubit. An insulator or tunnel barrier isolates the electrode system from the qubit during quantum computing. The electrode system can include a pair of electrodes for each qubit. A readout control system uses a voltmeter or other measurement device that connects to the electrode system, a current source, and grounding circuits. For a multi-qubit system, selection logic can select which qubit or qubits are read.

Abstract: Quantum computing systems and methods that use opposite magnetic moment states read the state of a qubit by applying current through the qubit and measuring a Hall effect voltage across the width of the current. For reading, the qubit is grounded to freeze the magnetic moment state, and the applied current is limited to pulses incapable of flipping the magnetic moment. Measurement of the Hall effect voltage can be achieved with an electrode system that is capacitively coupled to the qubit. An insulator or tunnel barrier isolates the electrode system from the qubit during quantum computing. The electrode system can include a pair of electrodes for each qubit. A readout control system uses a voltmeter or other measurement device that connects to the electrode system, a current source, and grounding circuits. For a multi-qubit system, selection logic can select which qubit or qubits are read.

Abstract: A solid state dc-SQUID includes a superconducting loop containing a plurality of Josephson junctions, wherein an intrinsic phase shift is accumulated through the loop. In an embodiment of the invention, the current-phase response of the dc-SQUID sits in a linear regime where directional sensitivity to flux through the loop occurs. Changes in the flux passing through the superconducting loop stimulates current which can be quantified, thus providing a means of measuring the magnetic field. Given the linear and directional response regime of the embodied device, an inherent current to phase sensitivity is achieved that would otherwise be unobtainable in common dc-SQUID devices without extrinsic intervention.