Resonant controlled qubit system
View Patent ↗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.
1. A circuit comprising:
a superconducting qubit having a qubit frequency between 0.8 GHz and 40 GHz;
a resonant control system that is characterized by a resonant frequency, wherein said resonant frequency is a function of a bias current, and wherein said resonant control system is an anharmonic resonator; and
a superconducting mechanism coherently coupled to the superconducting qubit and said resonant control system, wherein said superconducting mechanism has a capacitance or an inductance.
2. The circuit of claim 1 , wherein the resonant control system is superconducting.
3. The circuit of claim 1 , wherein said superconducting qubit is Josephson junction qubit.
4. The circuit of claim 1 wherein the capacitance or the inductance of the superconducting mechanism capacitively or inductively couples said superconducting qubit to said resonant control system.
5. A circuit comprising:
a superconducting qubit having a qubit frequency between 0.8 GHz and 40 GHz;
a resonant control system that is characterized by a resonant frequency, wherein said resonant frequency is a function of a bias current; and
a superconducting mechanism coherently coupled to the superconducting qubit and said resonant control system, wherein said superconducting mechanism has a capacitance or an inductance; wherein
the superconducting qubit is a charge qubit and said superconducting mechanism is a capacitor.
6. A circuit comprising:
a superconducting qubit having a qubit frequency between 0.8 GHz and 40 GHz;
a resonant control system that is characterized by a resonant frequency, wherein said resonant frequency is a function of a bias current; and
a superconducting mechanism coherently coupled to the superconducting qubit and said resonant control system, wherein said superconducting mechanism has a capacitance or an inductance; wherein
the resonant control system comprises a Josephson junction and a bias current source that is connected in series with the Josephson junction.
7. The circuit of claim 6 , wherein said bias current source is 0.994*I c or less, wherein I c is the critical current of said Josephson junction.
8. The circuit of claim 6 , wherein said bias current source is 0.990*I c or less, wherein I c is the critical current of said Josephson junction.
9. A circuit comprising:
a superconducting qubit having a qubit frequency between 0.8 GHz and 40 GHz;
a resonant control system that is characterized by a resonant frequency, wherein said resonant frequency is a function of a bias current; and
a superconducting mechanism coherently coupled to the superconducting qubit and said resonant control system, wherein said superconducting mechanism has a capacitance or an inductance; and
a readout mechanism for reading the quantum state of said superconducting qubit, wherein said readout mechanism is in electrical communication with said superconducting qubit.
10. The circuit of claim 9 , wherein said readout mechanism comprises a Josephson junction, a current source, a ground, and a voltmeter connected in parallel.
11. A circuit comprising:
a superconducting qubit having a qubit frequency between 0.8 GHz and 40 GHz;
a resonant control system that is characterized by a resonant frequency, wherein said resonant frequency is a function of a bias current; and
a superconducting mechanism coherently coupled to the superconducting qubit and said resonant control system, wherein said superconducting mechanism has a capacitance or an inductance; wherein said superconducting qubit is characterized by a native interaction Hamiltonian that includes an all off diagonal interaction term.
12. A circuit comprising:
a superconducting qubit having a qubit frequency between 0.8 GHz and 40 GHz;
a resonant control system that is characterized by a resonant frequency, wherein said resonant frequency is a function of a bias current; and
a superconducting mechanism coherently coupled to the superconducting qubit and said resonant control system, wherein said superconducting mechanism has a capacitance or an inductance; wherein
said superconducting qubit is characterized by a native interaction Hamiltonian that includes an all diagonal interaction term.
13. The circuit of claim 12 , wherein said superconducting qubit is charge qubit, a phase qubit, or a flux qubit.
14. A quantum register, comprising:
an array of superconducting qubits;
at least one resonant control system having a characteristic resonance frequency; and
a bus mechanism for capacitively or inductively coupling each superconducting qubit in said array of superconducting qubits to a resonant control system in said at least one resonant control system.
15. The quantum register of claim 14 , wherein a resonant control system in said at least one resonant control system comprises a Josephson junction and a bias current source that is in electrical communication with said Josephson junction, and wherein said characteristic resonance frequency is determined by a bias current provided by said bias current source.
16. The quantum register of claim 15 , wherein said bias current source is 0.994*I c or less, wherein I c is the critical current of said Josephson junction.
17. The quantum register of claim 15 , wherein said bias current source is 0.990*I c or less, wherein I c is the critical current of said Josephson junction.
18. The quantum register of claim 14 , wherein a resonant control system in said at least one resonant control system is an anharmonic resonator.
19. The quantum register of claim 14 , wherein said bus mechanism comprises a plurality of segments and wherein at least a first segment in said plurality of segments capacitively couples a plurality of qubits in said array of qubits to a resonant control system in said at least one resonant control system.
20. The quantum register of claim 19 , wherein said plurality of qubits comprises two qubits in said array of superconducting qubits.
21. The quantum register of claim 19 , wherein said plurality of qubits comprises three or more qubits in said array of superconducting qubits.
22. The quantum register of claim 19 , wherein said bus mechanism further comprises an inter-segment region between said first segment and a second segment in said plurality of segments, and wherein said inter-segment region comprises:
a first coherent superconducting switch that joins said inter-segment region to said first segment; and
a second coherent superconducting switch that joins said inter-segment region to said second segment.
23. The quantum register of claim 22 , wherein said first coherent superconducting switch is a first superconducting single electron transistor (SSET) and said second coherent superconducting switch is a second SSET.
24. The quantum register of claim 22 , wherein a superconducting pivot qubit is capacitively coupled with said inter-segment region.
25. The quantum register of claim 14 , wherein said bus mechanism comprises a plurality of segments, wherein a segment in said plurality of segments is capacitively coupled to a group of qubits in said array of qubits and wherein said segment is coupled to a resonant control system in said at least one resonant control system.
26. The quantum register of claim 14 , wherein said array of superconducting qubits comprises a charge qubit that is capacitively coupled to said bus mechanism.
27. The quantum register of claim 14 , wherein the array of superconducting qubits comprises a first qubit and a second qubit and wherein said first qubit is a different type of qubit than said second qubit.
28. The quantum register of claim 14 , wherein said array of superconducting qubits comprises a qubit that is described by a native interaction Hamiltonian that includes an off diagonal interaction term.
29. The quantum register of claim 28 , wherein said qubit is a superconducting charge qubit.
30. The quantum register of claim 14 , wherein said array of superconducting qubits comprises a qubit that is described by a native interaction Hamiltonian that includes a diagonal interaction term.
31. The quantum register of claim 30 , wherein said qubit is a charge qubit, a phase qubit, or a flux qubit.