Brandl M F, van Mourik M W, Postler L, Nolf A, Lakhmanskiy K, Paiva R R, Möller S, Daniilidis N, Häffner H, Kaushal V, Ruster T, Warschburger C, Kaufmann H, Poschinger U G, Schmidt-Kaler F, Schindler P, Monz T, Blatt R
Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.
Department of Physics, University of California, Berkeley, California 94720, USA.
Rev Sci Instrum. 2016 Nov;87(11):113103. doi: 10.1063/1.4966970.
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 alternating magnetic field noise, resulting in 120 dB reduction of 50 Hz noise along the magnetic field axis. We combine this efficient magnetic 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 optical qubits due to the motion of the cryostat. We measure 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 with Ca and Sr ions. The instability of the laser manipulating the optical qubits in Ca is characterized by yielding a minimum of its Allan deviation of 2.4 ⋅ 10 at 0.33 s. To evaluate the performance of the apparatus, we trapped Ca 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.
我们报告了一种用于囚禁离子量子计算的低温装置的设计，该装置包含一个分段表面电极阱。我们的低温恒温器的热屏蔽旨在衰减交变磁场噪声，从而使沿磁场轴的50 Hz噪声降低120 dB。我们通过在内层热屏蔽内放置两个数值孔径均为0.23的透镜，将这种高效的磁屏蔽与单离子寻址以及高效态检测所需的高光学可达性相结合。低温恒温器的设计采用了隔振措施，以避免由于低温恒温器的运动导致光学量子比特的退相干。我们测量了低温恒温器在2 s内小于±20 nm的振动。除了低温装置外，我们还描述了使用Ca和Sr离子进行操作所需的设置。操纵Ca中光学量子比特的激光器的不稳定性表现为在0.33 s时其阿伦偏差的最小值为2.4⋅10。为了评估该装置的性能，我们囚禁了Ca离子，获得了2.14(16)个声子/秒的加热速率和1/e时间为18.2(8) ms的拉姆齐对比度的高斯衰减。
