The establishment of a scalable, addressable, and long-lived scheme for quantum computing would be a scientific watershed, harnessing the laws of quantum physics to solve classically intractable problems. Many proposed computational platforms are driven by competing needs: isolating the quantum system from the environment to prevent decoherence, and easily and accurately controlling the system with external fields. For example, neutral-atom optical-lattice architectures provide environmental isolation through the use of states that are robust against fluctuating external fields, yet external fields are inherently useful for qubit addressing. Here we demonstrate a technique to address qubits formed from a pair of field-insensitive states by transferring the qubit into a different pair of field-insensitive states. A spatially inhomogeneous external field allows the addressing of particular "marked" elements of a qubit register, leaving unmarked qubits unaffected, despite the presence of crosstalk or leakage of the addressing field. We demonstrate this technique in an ensemble of Rb atoms and show that we can robustly perform single-qubit rotations on qubits located at addressed lattice sites. This precise coherent control is an important step forward for lattice-based neutral-atom quantum computation, and is applicable to state transfer and qubit isolation in other architectures using field-insensitive qubits.
Citation: Nature Physics
Pub Type: Journals
Bose-Einstein Condensate (BEC), optical lattices, quantum computation, ultracold atoms