Speaker
Description
Scalable quantum computing architectures require the ability to individually address qubits, maintain long coherence times relative to gate times, and support arbitrary qubit connectivity. We are developing a quantum processor architecture based on modular ion traps and physical ion shuttling, this allows for maximum connectivity, as well as zones dedicated for loading, coherent operations and measurements (Lekitsch, B. et. al. 2017). Coherent operations are performed in a magnetic field gradient, to allow for spin-motion coupling and the use of global microwave fields. Before transporting ions, magnetic gradients are ramped down to preserve qubit coherence.
In this work, we demonstrate the feasibility of this architecture by implementing randomised benchmarking of dressed state qubits in Yb171+, interleaved with gradient ramping, dressed state mapping and ion transport.
Randomised single qubit gates are performed on a multi-level dressed state basis in the presence of a magnetic field gradient. The qubit is mapped into a clock state, using protocols described in (Randall J. et. al. 2018). We calibrate the transition frequencies of our bare states and implement power matching techniques to achieve dressed state mapping with errors below 1×10^(-4).
We characterise the ramping of the magnetic field gradient using the ion as a magnetic field sensor. The gradient is ramped within a few microseconds using an external current source, incurring average errors below 1×10^(-2).
We also characterise the error from interleaved ion transport for a total distance of 240 μm in 140 μs and demonstrate average errors below 1×10^(-4). Finally, we measure a total process error, demonstrating that with appropriate calibration we maintain the individual quantum state of single qubits to high fidelity throughout the interleaved ion reconfiguration. The results validate an important core element of the proposed operational protocol and confirm the practicality of this modular architecture.
Lekitsch, B. et al. (2017) ‘Blueprint for a microwave trapped ion quantum computer’, Science Advances, 3(2), p. e1601540. doi:10.1126/sciadv.1601540.
Randall, J. et al. (2018) ‘Generation of high-fidelity quantum control methods for multilevel systems’, Physical Review A, 98(4), p. 043414. doi:10.1103/PhysRevA.98.043414.
| Academic level | PhD student |
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