State Perperation on Quantum Computers via Quantum Steering

We investigate a novel approach for state preparation on quantum computers through measurement-induced quantum steering. Combing passive reset (thermalization), active reset (projective-measurements), and discrete quantum gates, the approach reduces the number of qubits that undergo expensive active resets, avoids any classical processing during quantum computation for correction, and can prepare arbitrary states. By delegating ancilla qubits and systems qubits, the initial states are prepared by repeatedly performing the following steps: (1) executing a designated system-ancilla entangling operation, (2) measuring the ancilla qubits, and (3) re-initializing ancilla qubits to known states through active reset. With a digitized version of the entanglment operation, the ancilla qubits are measured and reinitialized to a known states, and the system qubits are steered from arbitrary initial states to desired final states. We experimentally realize our approach on a number of cloud-accessible quantum computers, noting performance qualities and noise levels of the contemporary quantum devices.