Abstract: Systems and methods are provided for resetting a qubit comprising a superconducting loop and a compound Josephson junction. A first bias flux is provided to the superconducting loop. A second bias flux is provided to the compound Josephson junction. Each of the first bias flux and the second bias flux are provided such that a given excited state of the qubit is near a top of a potential barrier associated with a potential of the qubit. A continuous microwave signal is generated having a frequency equal to a transition frequency between an other excited state of the qubit and the given excited state.

Abstract: Systems and methods are provided for flux control of a qubit. A quantum system includes a microwave transmitter configured to provide a continuous microwave tone, and a qubit configured such that transition energy of the qubit between a ground state of the qubit and a first excited state of the qubit is tunable via an applied flux. The qubit also has an inductive element responsive to the continuous microwave tone to produce a Rabi oscillation within the qubit. A flux source is configured to apply a flux to the qubit to selectively tune the transition energy of the qubit, such that the transition energy of the qubit can be tuned to a frequency of the Rabi oscillation or detuned from the Rabi oscillation.

Abstract: Systems and methods are provided for flux control of a qubit. A quantum system includes a microwave transmitter configured to provide a continuous microwave tone, and a qubit configured such that transition energy of the qubit between a ground state of the qubit and a first excited state of the qubit is tunable via an applied flux. The qubit also has an inductive element responsive to the continuous microwave tone to produce a Rabi oscillation within the qubit. A flux source is configured to apply a flux to the qubit to selectively tune the transition energy of the qubit, such that the transition energy of the qubit can be tuned to a frequency of the Rabi oscillation or detuned from the Rabi oscillation.

Abstract: A push-pull tunable coupler includes a push transformer, a pull transformer and two compound Josephson junctions arranged in upper and lower branches. Absent biasing, the balanced push and pull of current between the branches causes current from a first object to circulate within a loop and not to be coupled to a second object. Biasing of at least one of the compound Josephson junctions unbalances the push and pull of current in the branches to couple the first and second objects. The coupler has reduced sensitivity to differential-mode noise around the off state, is completely insensitive to common-mode noise, and is capable of inverting the coupled signal with appropriate relative biasing of the compound Josephson junctions.

Abstract: A method of producing carbon nanotubes includes directing a flow of a gas over a substrate to provide growth of at least one carbon nanotube in a carbon-nanotube-growth region of the substrate; applying an electric field to the carbon-nanotube-growth region of the substrate after the at least one carbon nanotube has begun to grow in the carbon-nanotube-growth region, the electric field being substantially in a first direction in the carbon-nanotube-growth region; and changing the electric field at a preselected time to be substantially in a second direction in the carbon-nanotube-growth region during growth of the at least one carbon nanotube. The second direction is different from the first direction resulting in a bend substantially at a selected position of the at least one carbon nanotube, the method of producing carbon nanotubes providing the production of the at least one carbon nanotube having at least one bend substantially at a selected position along the at least one carbon nanotube.

Abstract: A method of producing carbon nanotubes includes directing a flow of a gas over a substrate to provide growth of at least one carbon nanotube in a carbon-nanotube-growth region of the substrate; applying an electric field to the carbon-nanotube-growth region of the substrate after the at least one carbon nanotube has begun to grow in the carbon-nanotube-growth region, the electric field being substantially in a first direction in the carbon-nanotube-growth region; and changing the electric field at a preselected time to be substantially in a second direction in the carbon-nanotube-growth region during growth of the at least one carbon nanotube. The second direction is different from the first direction resulting in a bend substantially at a selected position of the at least one carbon nanotube, the method of producing carbon nanotubes providing the production of the at least one carbon nanotube having at least one bend substantially at a selected position along the at least one carbon nanotube.

Abstract: A method of producing carbon nanotubes includes directing a flow of a gas over a substrate to provide growth of at least one carbon nanotube in a carbon-nanotube-growth region of the substrate; applying an electric field to the carbon-nanotube-growth region of the substrate after the at least one carbon nanotube has begun to grow in the carbon-nanotube-growth region, the electric field being substantially in a first direction in the carbon-nanotube-growth region; and changing the electric field at a preselected time to be substantially in a second direction in the carbon-nanotube-growth region during growth of the at least one carbon nanotube. The second direction is different from the first direction resulting in a bend substantially at a selected position of the at least one carbon nanotube, the method of producing carbon nanotubes providing the production of the at least one carbon nanotube having at least one bend substantially at a selected position along the at least one carbon nanotube.