We advocate for a fundamentally different way to perform quantum computation by using three-level qutrits instead of qubits. In particular, we substantially reduce the resource requirements of quantum computations by exploiting a third state for temporary variables (ancilla) in quantum circuits. Past work with qutrits has demonstrated only constant factor improvements, owing to the log2(3) binary-to-ternary compression factor. We present a novel technique using qutrits to achieve a logarithmic runtime decomposition of the Generalized Toffoli gate using no ancilla---an exponential improvement over the best qubit-only equivalent. Our approach features a 70x improvement in total two-qudit gate count over the qubit-only decomposition. This results in improvements for important algorithms for arithmetic and QRAM. Simulation results under realistic noise models indicate over 90% mean reliability (fidelity) for our circuit, versus under 30% for the qubit-only baseline. These results suggest that qutrits offer a promising path toward extending the frontier of quantum computers.

中文翻译：

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用 Qutrits 扩展量子计算机的前沿

我们提倡通过使用三级 qutrit 而不是 qubits 来执行量子计算的一种根本不同的方式。特别是，我们通过利用量子电路中临时变量（辅助）的第三种状态，大大减少了量子计算的资源需求。由于 log2(3) 二元到三元压缩因子，过去使用 qutrits 的工作仅证明了常数因子的改进。我们提出了一种新技术，使用 qutrits 来实现广义 Toffoli 门的对数运行时分解，不使用辅助装置——对最佳量子比特等效物的指数改进。我们的方法的特点是总的两个量子位门数比仅量子位分解提高了 70 倍。这导致了对算术和 QRAM 的重要算法的改进。真实噪声模型下的仿真结果表明，我们电路的平均可靠性（保真度）超过 90%，而纯量子比特基线的平均可靠性（保真度）低于 30%。这些结果表明，qutrits 为扩展量子计算机的前沿提供了一条有希望的途径。