The research aiming to cut back the physical-to-logical qubit overhead by constructing logic gates inside a single trapped ion.
Physicists on the College of Sydney have reported a common set of logic gates for Gottesman–Kitaev–Preskill (GKP) qubits constructed inside a single trapped ion. The work is revealed in Nature Physics.
The end result targets a core scaling downside. Right this moment, one helpful “logical” qubit typically wants many “bodily” qubits for error correction. Encoding logic in an oscillator can reduce that overhead. That’s the position of the GKP code.
Within the experiment, the crew used one ytterbium ion held in a Paul lure. A Paul lure confines a charged atom with radio-frequency and direct-current electrical fields inside a vacuum chamber. The ion’s movement then acts like a tiny spring–mass oscillator.
Two of those oscillators, known as radial vibrational modes as they’re perpendicular to the lure’s axis and saved two logical qubits. Operating logic inside one atom avoids wiring two separate ions for this step. The group carried out single-qubit operations and an entangling two-qubit gate between the 2 modes.
GKP encoding maps the oscillator’s steady variables (place and momentum) onto a grid of discrete states. Small shifts change into measurable errors that may be corrected. Logic then runs on these encoded states quite than on uncooked {hardware} states.
Management got here from lasers that couple the ion’s inner state to its movement. By driving motional “sidebands”, the crew ready, manipulated and entangled the modes. The authors describe an optimal-control technique to hold the encoded states from distorting throughout gates.
Gate design and calibration have been supported by quantum-control software program from Q-CTRL, a College of Sydney spin-out. This hyperlinks the lab protocol to instruments used throughout trapped-ion platforms.
The end result reveals that two error-correctable logical qubits will be saved and entangled inside one atom. It additionally reveals {that a} common gate set can run on GKP qubits in an ordinary trapped-ion setup at room temperature. The paper outlines subsequent steps in extending the gate library and connecting to multi-ion techniques.
