Systems and methods for applying flux to a quantum-coherent superconducting circuit
AssigneeNorthrop Grumman Systems Corporation
InventorsQuentin P. Herr, Ofer Naaman, Anna Y. Herr
Life of this patent
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Abstract
Systems and methods are provided for applying flux to a quantum-coherent superconducting circuit. In one example, a system includes a long-Josephson junction (LJJ), an inductive loop coupled to the LJJ and inductively coupled to the quantum-coherent superconducting circuit, and a single flux quantum (SFQ) controller configured to apply a SFQ pulse to a first end of the LJJ that propagates the SFQ pulse to a second end of the LJJ, while also applying a flux quantum to the inductive loop resulting in a first value of control flux being applied to the quantum-coherent superconducting circuit.
Claims18
A system for applying flux to a quantum-coherent superconducting circuit, the system comprising:
- a long-Josephson junction (LJJ);
- an inductive loop coupled to a midpoint of the LJJ, in parallel with the LJJ, and inductively coupled to the quantum-coherent superconducting circuit;
- and
- a single flux quantum (SFQ) controller configured to apply a combination of a positive single flux quantum (SFQ) pulse and a negative SFQ pulse with respect to at least one of a first end of the LJJ and a second end of the LJJ to set a flux quantum of the inductive loop to a first value of control flux and a second value of control flux, respectively, that is applied to the quantum-coherent superconducting circuit.
A system for applying flux to a quantum-coherent superconducting circuit, the system comprising:
- a long-Josephson junction (LJJ) implemented as a Josephson junction array in a long-Josephson-junction limit arrangement;
- an inductive loop coupled to the LJJ at a midpoint of the LJJ, in parallel with the LJJ, and inductively coupled to the quantum-coherent superconducting circuit;
- a DC source inductively coupled to the inductive loop to provide a DC flux bias to establish a half of flux quantum that establishes a bi-stable persistent current in the inductive loop that is initially in a first direction;
- and
- a single flux quantum (SFQ) controller configured to apply:
- a first negative single flux quantum (SFQ) pulse to a first end of the LJJ that propagates the first negative SFQ pulse to a second end of the LJJ, while also applying a flux quantum to the inductive loop resulting in a first value of control flux being applied to the quantum-coherent superconducting circuit;
- and
- a second negative SFQ pulse to the second end of the LJJ that propagates the second negative SFQ pulse to the first end of the LJJ, while also removing the flux quantum from the inductive loop resulting in a second value of control flux being applied to the quantum-coherent superconducting circuit.
A method for applying flux to a quantum-coherent superconducting circuit, the method comprising:
- applying a DC flux bias to an inductive loop coupled to a long-Josephson junction (LJJ), in parallel with the LJJ, and inductively coupled to the quantum-coherent superconducting circuit to establish a half of flux quantum that establishes a bi-stable persistent current in the inductive loop that is initially in a first direction;
- applying a combination of a positive single flux quantum (SFQ) pulse and a negative SFQ pulse with respect to at least one of a first end of the LJJ and a second end of the LJJ to set a flux quantum of the inductive loop to a first value of control flux and a second value of control flux, respectively, that is applied to the quantum-coherent superconducting circuit.
Dependencies are inferred from the claim text.