Surface ion traps are among the most promising technologies for scaling up quantum computing machines, but their complicated multi-electrode geometry can make some tasks, including compensation for stray electric fields, challenging both at the level of modeling and of practical implementation. Here we demonstrate the compensation of stray electric fields using a gradient descent algorithm and a machine learning technique, which trained a deep learning network. We show automated dynamical compensation tested against induced electric charging from UV laser light hitting the chip trap surface. The results show improvement in compensation using gradient descent and the machine learner over manual compensation. This improvement is inferred from an increase of the fluorescence rate of 78% and 96% respectively, for a trapped $^{171}$Yb$^+$ ion driven by a laser tuned to -7.8 MHz of the $^2$S$_{1/2}\leftrightarrow^2$P$_{1/2}$ Doppler cooling transition at 369.5 nm.
We minimize the stray electric field in a linear Paul trap quickly and accurately, by applying interferometry pulse sequences to a trapped ion optical qubit. The interferometry sequences are sensitive to the change of ion equilibrium position when the trap stiffness is changed, and we use this to determine the stray electric field. The simplest pulse sequence is a two-pulse Ramsey sequence, and longer sequences with multiple pulses offer a higher precision. The methods allow the stray field strength to be minimized beyond state-of-the-art levels, with only modest experimental requirements. Usi…
The fidelity of laser-driven quantum logic operations on trapped ion qubits tend to be lower than microwave-driven logic operations due to the difficulty of stabilizing the driving fields at the ion location. Through stabilization of the driving optical fields and use of composite pulse sequences, we demonstrate high fidelity single-qubit gates for the hyperfine qubit of a $^{171}\text{Yb}^+$ ion trapped in a microfabricated surface electrode ion trap. Gate error is characterized using a randomized benchmarking protocol, and an average error per randomized Clifford group gate of $3.6(3)\times1…
The quadrupole interaction between the Rydberg electronic states of a Rydberg ion and the radio frequency electric field of the ion trap is analyzed. Such a coupling is negligible for the lowest energy levels of a trapped ion but it is important for a trapped Rydberg ion due to its large electric dipole moment. This coupling cannot be neglected by the standard rotating-wave approximation because it is comparable to the frequency of the trapping electric field. We investigate the effect of the quadrupole coupling by performing a suitable effective representation of the Hamiltonian. For a single…
Precise control of charged particles in radio-frequency (Paul) traps requires minimising excess micromotion induced by stray electric fields. We present a method to detect and compensate such fields through amplitude modulation of the radio-frequency trapping field. Modulation at frequencies close to the motional modes of the trapped particle excites coherent motion whose amplitude linearly depends on the stray field. In trapped-ion experiments, this motion can be detected by recording the arrival times of photons scattered during laser cooling. Only a single laser beam is required to resolve …
Cryogenic Time-Division-Multiplexed Voltage Control for Scalable Trapped-Ion Quantum Processors
QuEL, Inc.（QuEL公司）；Center for Quantum Information and Quantum Biology, The University of Osaka（大阪大学量子信息与量子生物学中心）；International Center for Elementary Particle Physics (ICEPP), The University of Tokyo（东京大学 elementary 粒子物理国际中心）；Komaba Institute for Science (KIS), The University of Tokyo（东京大学驹场理学研究所）；e-trees. Japan, Inc.（e-trees日本公司）；RIKEN Center for Quantum Computing (RQC)（理化学研究所量子计算中心）；Inamori Research Institute for Science (InaRIS)（稻盛科学研究所）
We investigate theoretically the possibility for robust and fast cooling of a trapped atomic ion by transient interaction with a pre-cooled ion. The transient coupling is achieved through dynamical control of the ions' equilibrium positions. To achieve short cooling times we make use of shortcuts to adiabaticity by applying invariant-based engineering. We design these to take account of imperfections such as stray fields, and trap frequency offsets. For settings appropriate to a currently operational trap in our laboratory, we find that robust performance could be achieved down to $6.3$ motion…
Ion trap on borosilicate substrate with integrated femtosecond-laser-written waveguide
Universität Innsbruck（因斯布鲁克大学）；Infineon Technologies Austria AG（英飞凌奥地利股份公司）；Universität Graz（格拉茨大学）；JOANNEUM RESEARCH（约阿内姆研究）；Alpine Quantum Technologies GmbH（阿尔卑斯量子技术有限责任公司）
Demonstration of transport in an ion trap design for two-dimensional lattices
Institut für Experimentalphysik, Universität Innsbruck（因斯布鲁克大学实验物理研究所）；Infineon Technologies Austria AG（英飞凌奥地利股份公司）；Department of Physics, Stockholm University（斯德哥尔摩大学物理系）；Alpine Quantum Technologies GmbH（阿尔卑斯量子技术有限责任公司）
We report a numerical study of a linear ion trap that has segmented blades and biasing rods. Our system consists of radio frequency (rf) blades, dc blades with ten separate electrodes, and two biasing rods for compensating the ions' micromotion. After calculating the optical access for the ions, we find rf and dc voltages that result in a stable trapping configuration of $^{171}$Yb$^{+}$ ions. We also explore the micromotion compensation with the biasing rods, and calculate the influence of blade misalignment to the trap potential. Our work offers quantitative understanding of the trap archite…
In order to study interactions of atomic ions with ultracold neutral atoms, it is important to have sub-$μ$m control over positioning ion crystals. Serving for this purpose, we introduce a microfabricated planar ion trap featuring 21 DC electrodes. The ion trap is controlled by a home-made FPGA voltage source providing independently variable voltages to each of the DC electrodes. To assure stable positioning of ion crystals with respect to trapped neutral atoms, we integrate into the overall design a compact mirror magneto optical chip trap (mMOT) for cooling and confining neutral $^{87}$Rb at…
We propose a novel ion trap design with the high collection efficiency parabolic-mirror integrated with the ion trap electrodes. This design has three radio frequency (RF) electrodes and eight direct current(DC) compensation electrodes. By carefully adjusting three RF voltages, the parabolic mirror focus can be made precisely coincident with the RF null point. Thus, the aberration and the ion micromotion can be minimized at the same time. This monolithic design can significantly improve the ion-ion entanglement generation speed by extending the photon collecting solid angle beyond $90\%\cdot4π…
We introduce the use of two machine learning algorithms to create an empirical model of an experimental apparatus, which is able to reduce the number of measurements necessary for generic optimisation tasks exponentially as compared to unbiased systematic optimisation. Principal Component Analysis (PCA) can be used to reduce the degrees of freedom in cases for which a rudimentary model describing the data exists. We further demonstrate the use of an Artificial Neural Network (ANN) for tasks where a model is not known. This makes the presented method applicable to a broad range of different opt…
Paul traps are widely used to confine electrically charged particles like atomic and molecular ions by using an intense radiofrequency (RF) field, typically obtained by a voltage drop on capacitative electrodes placed in vacuum. We present a RF drive realized on a compact printed circuit board (PCB) and providing a high-voltage RF signal to a quadrupole Paul trap. The circuit is formed by four interdependent resonant circuits $-$ each of which connected to an electrode of a Paul trap $-$ fed by low-noise amplifiers, leading to an output voltage of peak-to-peak amplitude up to 200 V at 3.23 MHz…
A monolithic segmented 3D ion trap fabricated from fused silica by selective laser-induced etching
ETH Zürich–PSI Quantum Computing Hub（苏黎世联邦理工学院-保罗谢勒研究所量子计算中心）；Institute for Quantum Electronics, ETH Zürich（苏黎世联邦理工学院量子电子学研究所）；Department of Physics, University of Trieste（的里雅斯特大学物理系）；Oxford Ionics（牛津离子体公司）；NVIDIA（英伟达）；Nanophotonic Systems Laboratory, Department of Mechanical and Process Engineering, ETH Zurich（苏黎世联邦理工学院机械与工艺工程纳米光子学系统实验室）
Cold-Atom Buoy: A Differential Magnetic Sensing Technique in Cold Quadrupole Traps
HUN-REN Wigner Research Centre for Physics（匈牙利研究网络温格物理研究中心）；Department of Physics of Complex Systems, ELTE Eötvös Loránd University（厄特沃什·罗兰大学复杂系统物理系）；Center for Quantum Science, Physikalisches Institut, Eberhard Karls Universität Tübingen（蒂宾根大学物理研究所量子科学中心）；Department of Theoretical Physics, Institute of Physics, Budapest University of Technology and Economics（布达佩斯技术与经济大学物理研究所理论物理系）
Experimental realizations of charged ions and neutral atoms in overlapping traps are gaining increasing interest due to their wide research application ranging from chemistry at the quantum level to quantum simulations of solid-state systems. Here, we describe a system in which we overlap a single ground-state cooled ion trapped in a linear Paul trap with a cloud of ultracold atoms such that both constituents are in the $μ$K regime. Excess micromotion (EMM) currently limits atom-ion interaction energy to the mK energy scale and above. We demonstrate spectroscopy methods and compensation techni…
Three-dimensional three-photon Stark spectroscopy of a single Rb Rydberg atom in an ultrahigh-vacuum glass cell with eight electrodes
Rzhanov Institute of Semiconductor Physics SB RAS（列扎诺夫半导体物理研究所西伯利亚分院）；Novosibirsk State University（新西伯利亚国立大学）；Institute of Laser Physics SB RAS（激光物理研究所西伯利亚分院）
