Speaker
Description
Towards entanglement distribution between two surface ion trap quantum computing chips
T. Maddock, M. S. Brown, S. Weidt, W. K. Hensinger
The ability to generate and distribute entanglement in engineered quantum systems is a prerequisite for a fully-fledged quantum computer [1]. Our group has demonstrated rapid distribution of quantum information using a transport-baed approach between two surface ion trap quantum computing chips. This demonstration was limited to single-ion state encoding, meaning the next logical step is to entangle two ions and verify the preservation of entanglement following rapid two-ion separation, shuttling to the second module, and recombining.
In preparation for this work, the system has been retrofitted with working Current Carrying Wires (CCWs), enabling entangling operations using magnetic field gradients [2]. In preparation for work involving entanglement distribution, a small defect was found to obstruct linear shuttling between the modules; we found that we were able to ablate the chip as a cleaning technique, which restored shuttling success rates past where the link was formerly obstructed to near unity, with no damage to the chip itself.
Additionally, the use of globally applied microwave radiation has proven to enable useful quantum control interleaved with transport techniques. For instance, following qubit initialisation in the ground state, single-qubit rotations can be arbitrarily applied if dead times are used between shuttle (transport) legs, or indeed during ion transportation, with the ion at any point of the trap, not just allocated gate zones. This allows for mid-transport pulsed dynamical decoupling, which can reduce the effective clock cycle of quantum circuits. Additionally, by applying microwave pulses with variable delays from the start of shuttle playback, the ion frequency can be used analogously to a light gate, precisely indicating the ion’s position in time with extremely high precision.
With initial two-qubit gate data taken, in addition to ongoing ion separation work, we hope to demonstrate rapid distribution of Doppler-cooled trapped ion pairs between two surface ion traps, ultimately enabling distributed entanglement between modules [3].
References:
[1] B. Lekitsch et al., “Blueprint for a microwave trapped ion quantum computer”, Science Advances 3 (2017).
[2] M. S. Brown et al., “Fabrication of surface ion traps with integrated current carrying wires enabling high magnetic field gradients”, Quantum Science and Technology 7, 034003 (2022).
[3] M. Akhtar et al., “High-fidelity quantum links between trapped-ion modules”, Nature
| Academic level | PhD student |
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