Cryogenic setup for trapped ion quantum computing

We report on the design of a cryogenic setup for trapped ion quantum computing containing a segmented surface electrode trap. The heat shield of our cryostat is designed to attenuate alternatingmagnetic field noise, resulting in 120 dB reduction of 50 Hz noise along themagnetic field axis. We combine this efficientmagnetic shielding with high optical access required for single ion addressing as well as for efficient state detection by placing two lenses each with numerical aperture 0.23 inside the inner heat shield. The cryostat design incorporates vibration isolation to avoid decoherence of opticalqubits due to the motion of the cryostat. Wemeasure vibrations of the cryostat of less than ±20 nm over 2 s. In addition to the cryogenic apparatus, we describe the setup required for an operation with40Ca+ and88Sr+ ions. The instability of the laser manipulating the opticalqubits in40Ca+ is characterized by yielding a minimum of its Allan deviation of 2.4 ⋅ 10−15 at 0.33 s. To evaluate the performance of the apparatus, we trapped40Ca+ ions, obtaining a heating rate of 2.14(16) phonons/s and a Gaussian decay of the Ramsey contrast with a 1/e-time of 18.2(8) ms.

Source: Review of Scientific Instruments - November 8, 2016 Category: Physics Authors: M. F. Brandl, M. W. van Mourik, L. Postler, A. Nolf, K. Lakhmanskiy, R. R. Paiva, S. M öller, N. Daniilidis, H. Häffner, V. Kaushal, T. Ruster, C. Warschburger, H. Kaufmann, U. G. Poschinger, F. Schmidt-Kaler, P. Schindler, T. Monz and R. Blatt Source Type: research