Fault-tolerant quantum cat state preparation

A quantum device comprising:

• a cat state preparation circuit with fault tolerance t and circuit depth less than or equal to 4+4t, the cat state preparation circuit configured to:
• perform a sequence of joint parity measurements on individual pairs of neighboring qubits in a series of qubits entangled to form an initial cat state;
• repeat the sequence of measurements over at least t-rounds;
• and
• disentangle a first set of alternating qubits from the initial cat state to form a prepared cat state that is guaranteed with a predefined degree of certainty to include less than or equal to t number of faults, the prepared cat state being formed by a remaining second set of alternating qubits, the second set of alternating qubits being interlaced with the first set of alternating qubits along a line of one-dimensional connectivity.

One or more tangible computer readable storage media storing processor-executable instructions for executing a computer process to prepare a cat state in a quantum circuit with fault tolerance t and circuit depth less than or equal to 4+4t, the computer process comprising:

• performing a sequence of joint parity measurements on individual pairs of neighboring qubits in a series of qubits entangled to form an initial cat state;
• repeating the sequence of measurements over at least t-rounds;
• and
• disentangling a first set of alternating qubits from the initial cat state to form the prepared cat state with a remaining second set of alternating qubits, the second set of alternating qubits being interlaced with the first set of alternating qubits along a line of one-dimensional connectivity, the prepared cat state being guaranteed with a predefined degree of certainty to include less than or equal to t number of faults.