8 research outputs found
Rapid Exchange Cooling with Trapped Ions
The trapped-ion quantum charge-coupled device (QCCD) architecture is a
leading candidate for advanced quantum information processing. In current QCCD
implementations, imperfect ion transport and anomalous heating can excite ion
motion during a calculation. To counteract this, intermediate cooling is
necessary to maintain high-fidelity gate performance. Cooling the computational
ions sympathetically with ions of another species, a commonly employed
strategy, creates a significant runtime bottleneck. Here, we demonstrate a
different approach we call exchange cooling. Unlike sympathetic cooling,
exchange cooling does not require trapping two different atomic species. The
protocol introduces a bank of coolant ions which are repeatedly laser
cooled. A computational ion can then be cooled by transporting a coolant ion
into its proximity. We test this concept experimentally with two ions,
executing the necessary transport in 107 , an order of magnitude faster
than typical sympathetic cooling durations. We remove over 96%, and as many as
102(5) quanta, of axial motional energy from the computational ion. We verify
that re-cooling the coolant ion does not decohere the computational ion. This
approach validates the feasibility of a single-species QCCD processor, capable
of fast quantum simulation and computation
Characterization of Fast Ion Transport via Position-Dependent Optical Deshelving
Ion transport is an essential operation in some models of quantum information
processing, where fast ion shuttling with minimal motional excitation is
necessary for efficient, high-fidelity quantum logic. While fast and cold ion
shuttling has been demonstrated, the dynamics and specific trajectory of an ion
during diabatic transport have not been studied in detail. Here we describe a
position-dependent optical deshelving technique useful for sampling an ion's
position throughout its trajectory, and we demonstrate the technique on fast
linear transport of a ion in a surface-electrode ion trap.
At high speed, the trap's electrode filters strongly distort the transport
potential waveform. With this technique, we observe deviations from the
intended constant-velocity (100 m/s) transport: we measure an average speed of
83(2) m/s and a peak speed of 251(6) m/s over a distance of 120
Self-consistent model of spin accumulation magnetoresistance in ferromagnet/insulator/semiconductor tunnel junctions
Rapid exchange cooling with trapped ions
Abstract The trapped-ion quantum charge-coupled device (QCCD) architecture is a leading candidate for advanced quantum information processing. In current QCCD implementations, imperfect ion transport and anomalous heating can excite ion motion during a calculation. To counteract this, intermediate cooling is necessary to maintain high-fidelity gate performance. Cooling the computational ions sympathetically with ions of another species, a commonly employed strategy, creates a significant runtime bottleneck. Here, we demonstrate a different approach we call exchange cooling. Unlike sympathetic cooling, exchange cooling does not require trapping two different atomic species. The protocol introduces a bank of “coolant" ions which are repeatedly laser cooled. A computational ion can then be cooled by transporting a coolant ion into its proximity. We test this concept experimentally with two 40Ca+ ions, executing the necessary transport in 107 μs, an order of magnitude faster than typical sympathetic cooling durations. We remove over 96%, and as many as 102(5) quanta, of axial motional energy from the computational ion. We verify that re-cooling the coolant ion does not decohere the computational ion. This approach validates the feasibility of a single-species QCCD processor, capable of fast quantum simulation and computation