Quantum circuits with reduced T gate count
AssigneeGoogle Inc.
InventorCraig Gidney
Life of this patent
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Abstract
Methods, systems and apparatus for producing quantum circuits with low T gate counts. In one aspect, a method for performing a temporary logical AND operation on two control qubits includes the actions of obtaining an ancilla qubit in an A-state; computing a logical-AND of the two control qubits and storing the computed logical-AND in the state of the ancilla qubit, comprising replacing the A-state of the ancilla qubit with the logical-AND of the two control qubits; maintaining the ancilla qubit storing the logical-AND of the two controls until a first condition is satisfied; and erasing the ancilla qubit when the first condition is satisfied.
Claims16
A method for performing a temporary Toffoli quantum logic gate on two control qubits and a target qubit, the method comprising:
- storing a computed logical-AND of two control qubits in a state of an ancilla qubit prepared in an A-state;
- applying a CNOT quantum logic gate between (i) the ancilla qubit storing the logical-AND of the two control qubits, and (ii) the target qubit, the ancilla qubit acting as a control qubit for the CNOT quantum logic gate;
- providing the ancilla qubit storing the logical-AND of the two control qubits as a resource for one or more additional operations;
- and
- replacing the state of the ancilla qubit storing the computed logical-AND of the two control qubits with an A-state.
A quantum computing device comprising:
- a register of qubits comprising two control qubits, a target qubit, and an ancilla qubit prepared in an initial state;
- a plurality of control lines coupled to the register of qubits;
- a plurality of control circuits coupled to the plurality of control lines, the plurality of control circuits configured to perform operations comprising:
- storing a computed logical-AND of two control qubits in a state of an ancilla qubit prepared in an A-state;
- applying a CNOT quantum logic gate between (i) the ancilla qubit storing the logical-AND of the two control qubits, and (ii) the target qubit, the ancilla qubit acting as a control qubit for the CNOT quantum logic gate;
- providing the ancilla qubit storing the logical-AND of the two control qubits as a resource for one or more additional operations;
- and
- replacing the state of the ancilla qubit storing the computed logical-AND of the two control qubits with an A-state.
Dependencies are inferred from the claim text.