HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA.
Phys Rev Lett. 2016 Mar 18;116(11):110402. doi: 10.1103/PhysRevLett.116.110402. Epub 2016 Mar 16.
We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity of exchange operations to charge noise. The method involves biasing a double dot symmetrically between the charge-state anticrossings, where the derivative of the exchange energy with respect to gate voltages is minimized. Exchange remains highly tunable by adjusting the tunnel coupling. We find that this method reduces the dephasing effect of charge noise by more than a factor of 5 in comparison to operation near a charge-state anticrossing, increasing the number of observable exchange oscillations in our qubit by a similar factor. Performance also improves with exchange rate, favoring fast quantum operations.
我们通过显著降低交换操作对电荷噪声的敏感性来改善交换耦合半导体量子点的性能。该方法包括在电荷态交叉点之间对双量子点进行对称偏置，在该处交换能对栅极电压的导数最小化。通过调整隧道耦合，交换仍然可以高度可调。我们发现与在电荷态交叉点附近操作相比，这种方法将电荷噪声的退相效应降低了 5 倍以上，使我们的量子位中可观察到的交换振荡数量增加了相同的倍数。性能也随着交换速率的提高而提高，有利于快速量子操作。
