Quantum Computers: 99.992% Accuracy with Atom Transfer

A new method for fast and coherent transfer of atomic qubits in optical tweezers is demonstrated by Jia-Chao Wang and colleagues at Wuhan Institute of Physics and Mathematics. The method uses a new fibre array architecture to address key limitations in transfer speed and motional heating, achieving in situ transfer within 10μs and sustaining over 500 cycles with minimal atom loss. The advancement yields a quantum state fidelity exceeding 0.99992 per cycle, providing a practical pathway towards building faster and more accurate atom-shuttling based quantum computers.

High-fidelity, rapid qubit transfer unlocks extended quantum computation

Quantum state fidelity exceeded 0.99992 per cycle, a substantial improvement over prior methods limited to lower values and slower transfer rates. This breakthrough crosses a critical threshold for fault-tolerant quantum computation, where maintaining qubit coherence is vital. Previously, such high fidelity combined with speed was unattainable due to the accumulation of errors during qubit manipulation. Achieving this level of precision enables more complex quantum algorithms and extended computation times.

The system sustains over 500 cycles with negligible atom loss, further solidifying its potential for scalable quantum processors. A transfer speed of 10 microseconds between static and moving traps establishes a benchmark for rapid qubit manipulation. In particular, the system achieved a per-cycle heating rate of only 0.156 microKelvin, minimising unwanted energy input during the transfer process; this low heating is essential for maintaining qubit coherence over extended computational periods.

Detailed analysis of parallel transfers revealed a direct relationship between array imperfections and heating rates, allowing for potential optimisation strategies. Inter-site transfer between static traps took 120 microseconds with 0.783 microKelvin of heating. While these figures represent a significant advance, they do not yet account for the complexities of controlling hundreds or thousands of qubits simultaneously, where cumulative errors and crosstalk could still present substantial challenges.

Rapid atom transfer sustains high fidelity during hundreds of quantum cycles

Neutral-atom quantum computers promise scalability by physically moving qubits, individual atoms, around a chip to create connections and perform calculations. This work delivers a significant speed boost to that movement, achieving transfers in just tens of microseconds and sustaining performance for hundreds of cycles. David Nadlinger, Seiji Suzuki, and colleagues acknowledge a current limitation. They demonstrate strong transfers for up to 500 cycles in one configuration and 100 in another, but building a truly useful quantum computer demands millions of operations.

Hundreds of cycles represent a vital engineering step forward, even though it is short of the millions needed for a fully functional quantum computer. These results demonstrate markedly improved qubit movement, a fundamental challenge in building these machines, and above all, do so with minimal loss of quantum information, measured as fidelity. Maintaining coherence, the delicate state enabling quantum calculations, during these atomic ‘shuttles’ is vital; previous methods suffered from significant heating and errors.

Precise control of atom trapping and a fibre array architecture enabled scientists to achieve minimal energy gain, known as motional heating, during qubit movement. Sustaining high fidelity through hundreds of cycles confirms the potential for scalable, atom-shuttling quantum computers, crucial as quantum calculations require numerous operations. Further investigation will focus on understanding how imperfections within the array influence heating rates, paving the way for optimisation and, ultimately, larger and more reliable quantum processors.

Rapid and coherent transfer of neutral atoms was demonstrated, sustaining quantum state fidelity of 0.99992 over 500 cycles and 0.9998 over 100 cycles. This achievement matters because minimising energy gain during qubit movement, achieved here with a heating rate of 0.156 μK per cycle, is essential for performing complex quantum calculations. Researchers established a model linking array imperfections to heating rates, suggesting future work will focus on optimising these systems. This advance represents a practical step towards scalable quantum computing based on atom-shuttling architectures.