摘要:
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.
摘要:
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. The superconducting loop further includes first and second Josephson junctions separating the bulk loop portion from the mesoscopic island portion. The superconducting loop further includes a third Josephson junction in the bulk loop portion. In one embodiment, the third Josephson junction has a Josephson energy relatively larger than a Josephson energy of the first and second Josephson junctions.
摘要:
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.
摘要:
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. The states of two qubits can be entangled by coupling the two qubits through a switch. In some embodiments, the switch that is capable of grounding the qubits can also be utilized for entangling selected qubits.
摘要:
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. The states of two qubits can be entangled by coupling the two qubits through a switch. In some embodiments, the switch that is capable of grounding the qubits can also be utilized for entangling selected qubits.
摘要:
A solid-state quantum computing qubit includes a multi-terminal junction coupled to a superconducting loop where the superconducting loop introduces a phase shift to the superconducting order parameter. The ground state of the supercurrent in the superconducting loop and multi-terminal junction is doubly degenerate, with two supercurrent ground states having distinct magnetic moments. These quantum states of the supercurrents in the superconducting loop create qubits for quantum computing. The quantum states can be initialized by applying transport currents to the external leads. Arbitrary single qubit operations may be performed by varying the transport current and/or an externally applied magnetic field. Read-out may be performed using direct measurement of the magnetic moment of the qubit state, or alternatively, radio-frequency single electron transistor electrometers can be used as read-out devices when determining a result of the quantum computing. Further, qubits as described above can form arrays of qubits for performing controlled quantum computing calculations. In one example, an array of qubits can be utilized as a random number generator.
摘要:
A solid-state quantum computing qubit includes a multi-terminal junction coupled to a superconducting loop where the superconducting loop introduces a phase shift to the superconducting order parameter. The ground state of the supercurrent in the superconducting loop and multi-terminal junction is doubly degenerate, with two supercurrent ground states having distinct magnetic moments. These quantum states of the supercurrents in the superconducting loop create qubits for quantum computing. The quantum states can be initialized by applying transport currents to the external leads. Arbitrary single qubit operations may be performed by varying the transport current and/or an externally applied magnetic field. Read-out may be performed using direct measurement of the magnetic moment of the qubit state, or alternatively, radio-frequency single electron transistor electrometers can be used as read-out devices when determining a result of the quantum computing. Further, qubits as described above can form arrays of qubits for performing controlled quantum computing calculations. In one example, an array of qubits can be utilized as a random number generator.
摘要:
A method is described for forming a solid state qubit. The method includes forming a dot or an anti-dot. The dot or anti-dot can be formed on a substrate and is delimited by an interface that defines a closed area. The dot or anti-dot includes a superconductive material with Cooper pairs that are in a state of non-zero orbital angular momentum on at least one side of the interface. The method includes removing superconducting material on the inner side of the interface or removing the outer side of the interface by etching. The method can further include forming a dot or an anti-dot by damaging the superconducting material such that the superconductive material becomes non-superconductive in predefined areas. The damaging of superconducting material can be performed by irradiation with particles, such as alpha particles or neutrons. The superconductive material can also be formed by doping a non-superconductive material.
摘要:
A quantum computing structure comprising a superconducting phase-charge qubit, wherein the superconducting phase-charge qubit comprises a superconducting loop with at least one Josephson junction. The quantum computing structure also comprises a first mechanism for controlling a charge of the superconducting phase-charge qubit and a second mechanism for detecting a charge of the superconducting phase-charge qubit, wherein the first mechanism and the second mechanism are each capacitively connected to the superconducting phase-charge qubit.
摘要:
A solid-state quantum computing structure includes a dot of superconductive material, where the superconductor possesses a dominant order parameter with a non-zero angular momentum and a sub-dominant order parameter that can have any pairing symmetry. Alternately a solid-state quantum computing structure includes an anti-dot, which is a region in a superconductor where the order parameter is suppressed. In either embodiment of the invention, circulating persistent currents are generated via time-reversal symmetry breaking effects in the boundaries between superconducting and insulating materials. These effects cause the ground state for the supercurrent circulating near the qubit to be doubly degenerate, with two supercurrent ground states having distinct magnetic moments. These quantum states of the supercurrents store quantum information, which creates the basis of qubits for quantum computing. Writing to the qubits and universal single qubit operations may be performed via the application of magnetic fields. Read-out of the information may be performed using a SQUID microscope or a magnetic force microscope.