Quantum gates via multi-step adiabatic drag
AssigneeNorthrop Grumman Systems Corporation
InventorRyan J. Epstein
Life of this patent
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Abstract
Systems and methods are provided for performing a quantum gate operation. The system includes a first physical qubit, and a second physical qubit operatively coupled to the first physical qubit via a coupling mechanism. The first physical qubit, the second physical qubit, and the coupling mechanism form a logical qubit. At least one control mechanism is configured to provide a control signal to one of the first physical qubit, the second physical qubit, and the coupling mechanism as to adjust a Hamiltonian of the logical qubit.
Claims19
A system for performing a quantum gate operation that is highly resilient to noise on control signals, the system comprising:
- a plurality of physical qubits comprising a first physical qubit and a second physical qubit;
- at least one coupling mechanism are configured such that each coupling mechanism operatively couples at most two qubits, the plurality of physical qubits, and the at least one coupling mechanism forming at least one logical qubit;
- and
- at least one control mechanism, configured to provide a control signal to one of the first physical qubit, the second physical qubit, and the coupling mechanism as to adiabatically adjust a Hamiltonian of the logical qubit from a first Hamiltonian to a second Hamiltonian by adjusting a coupling strength of a coupling mechanism of the at least one coupling mechanism from zero to a non-zero value;
- wherein a number of physical qubits in the system is at most twice a number of logical qubits.
A method for performing a universal quantum gate set that is highly resistant to noise on control signals comprising:
- preparing each of a first physical qubit and a second physical qubit of a plurality of physical qubits coupled by at least one coupling mechanism, such that each coupling mechanism couples at most two of the plurality of physical qubits, in a ground state associated with a first Hamiltonian associated with the quantum gate;
- applying a first control signal to system such that a Hamiltonian of the system is the first Hamiltonian of the system, the system comprising a plurality of logical qubits formed from the plurality of physical qubits and the at least one coupling mechanism such that a number of physical qubits in the system is at most twice a number of logical qubits;
- performing an adiabatic interpolation of the Hamiltonian of the system from the first Hamiltonian to a second Hamiltonian adiabatically, by adjusting a coupling strength of the coupling mechanism from zero to a non-zero value using the second control signal;
- and
- performing an adiabatic interpolation of the Hamiltonian of the system from the second Hamiltonian to a third Hamiltonian.
A method for performing a quantum gate comprising:
- preparing each of a first physical qubit and a second physical qubit of a plurality of physical qubits coupled by at least one coupling mechanism, such that each coupling mechanism couples at most two of the plurality of physical qubits, in a ground state associated with a first Hamiltonian of a system comprising a plurality of logical qubits formed from the plurality of physical qubits and the at least one coupling mechanism such that a number of physical qubits in the system is at most twice a number of logical qubits;
- applying a first control signal to the system such that the energy level of a first X eigenstate of the second physical qubit is increased relative to an energy level of a second X eigenstate of the second physical qubit;
- performing a first adiabatic interpolation of the Hamiltonian of the system, such that the first control signal is ramped down to change the strength of the first Hamiltonian from non-zero to zero while a second control signal is ramped up to change the coupling strength of the coupling mechanism from zero to a non-zero value;
- and
- performing a second adiabatic interpolation of the Hamiltonian of the system such that the energy level of a first eigenstate of one of the first and second physical qubits along a defined axis of the Bloch sphere is increased relative to an energy level of a second eigenstate of the one of the first and second physical qubits while the coupling strength of the coupling mechanism is returned to zero.
Dependencies are inferred from the claim text.