'Rosetta Stone' of Code Shrinks Quantum Computer Hardware Needs

alternative_right shares a report from Phys.org: Now, for the first time, quantum scientists at the Quantum Control Laboratory at the University of Sydney Nano Institute have demonstrated a type of quantum logic gate that drastically reduces the number of physical qubits needed for its operation. To do this, they built an entangling logic gate on a single atom using an error-correcting code nicknamed the 'Rosetta stone' of quantum computing. It earns that name because it translates smooth, continuous quantum oscillations into clean, digital-like discrete states, making errors easier to spot and fix, and importantly, allowing a highly compact way to encode logical qubits.
The curiously named Gottesman-Kitaev-Preskill (GKP) code has for many years offered a theoretical possibility for significantly reducing the physical number of qubits needed to produce a functioning 'logical qubit.' Albeit by trading efficiency for complexity, making the codes very difficult to control. Research published in Nature Physics demonstrates this as a physical reality, tapping into the natural oscillations of a trapped ion (a charged atom of ytterbium) to store GKP codes and, for the first time, realizing quantum entangling gates between them.

Led by Sydney Horizon Fellow Dr. Tingrei Tan at the University of Sydney Nano Institute, scientists have used their exquisite control over the harmonic motion of a trapped ion to bridge the coding complexity of GKP qubits, allowing a demonstration of their entanglement. 'Our experiments have shown the first realization of a universal logical gate set for GKP qubits,' Dr. Tan said. 'We did this by precisely controlling the natural vibrations, or harmonic oscillations, of a trapped ion in such a way that we can manipulate individual GKP qubits or entangle them as a pair.' Across three experiments described in the paper, Dr. Tan's team used a single ytterbium ion contained in what is known as a Paul trap. This uses a complex array of lasers at room temperature to hold the single atom in the trap, allowing its natural vibrations to be controlled and utilized to produce the complex GKP codes. This research represents an important demonstration that quantum logic gates can be developed with a reduced physical number of qubits, increasing their efficiency.

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