Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of ±10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.
Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of ±10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.
We report a design and implementation of a field-programmable-gate-arrays (FPGA) based hardware platform, which is used to realize control and signal readout of trapped-ion-based multi-level quantum systems. This platform integrates a four-channel 2.8 Gsps@14 bits arbitrary waveform generator, a 16-channel 1 Gsps@14 bits direct-digital-synthesis-based radio-frequency generator, a 16-channel 8 ns resolution pulse generator, a 10-channel 16 bits digital-to-analog-converter module, and a 2-channel proportion integration differentiation controller. The hardware platform can be applied in the trapped-ion-based multi-level quantum systems, enabling quantum control of multi-level quantum system and high-dimensional quantum simulation. The platform is scalable and more channels for control and signal readout can be implemented by utilizing more parallel duplications of the hardware. The hardware platform also has a bright future to be applied in scaled trapped-ion-based quantum systems.
This paper reports the development of a low-latency arbitrary waveform generator (AWG), which is suitable for the control and measurement of superconducting quantum computers. It can generate qubit control signals and measurement signals in real time. Compared with commercial AWG, our AWG has less latency and higher analog bandwidth. Compressing latency can reduce system feedback time, and higher analog bandwidth improves the system's integration by mounting more qubits on the readout line. The AWG integrates four high-speed digital-to-analog converters (DACs), phase-locked loop (PLL) circuits, field-programmable gate arrays (FPGAs), and related circuits into a standard PXI 3U board. The waveform generator module, communication interface module, clock module, and configuration module are realized utilizing the FPGA. The FPGA-based hardware architecture enables AWG to be flexibly configured to meet the various needs of quantum experiments. The four-channel AWG has a 2-GSa/s sampling rate, a 14-bit resolution, and 500 MHz bandwidth. The jitter in the AWG output waveform is approximately 3 ps; the latency of the AWG (the time from the feedback trigger received until a feedback pulse is generated) is approximately 55 ns. These designs form the basis of realizing control system for large-scale quantum computing.
We present a versatile rf pulse control system that has been designed for multi-qubit quantum experiments. One instrument can be scaled to provide 32 channels of rf between 10 - 450 MHz. Synchronization can be achieved across multiple instruments. By using direct digital synthesis and custom control circuitry contained within a field-programmable gate array, sequences of transform-limited pulses can be produced. These have been used to carry out quantum gates that are able to meet fault-tolerant thresholds for single- and two-qubit gate fidelities, as published elsewhere. We have also extended the frequency to the gigahertz regime using additional mixers to address hyperfine transitions in atomic systems. The system uses an efficient memory management scheme and a low-latency communications protocol that allows pulse sequences to be updated in real-time. Together these can enable outcome-based algorithms such as quantum error correction to be executed. The system is fully programmable in C++, and other languages such as Python can be supported by the on-board CPU, offering a highly flexible platform for a wide variety of experimental systems, and has been proven in trapped-ion quantum information experiments.
The scaling up of trapped-ion quantum processors based on the quantum charge-coupled device (QCCD) architecture is difficult owing to the extensive electronics and high-density wiring required to control numerous trap electrodes. In conventional QCCD architectures, each trap electrode is controlled via a dedicated digital-to-analog converter (DAC). The conventional approach places an overwhelming demand on electronic resources and wiring complexity. This is because the number of trap electrodes typically exceeds the number of trapped-ion qubits. This study proposes a method that leverages a high-speed DAC to generate time-division multiplexed signals to control a large-scale QCCD trapped-ion quantum processor. The proposed method replaces conventional DACs with a single high-speed DAC that generates the complete voltage waveforms required to control the trap electrodes, thereby significantly reducing the wiring complexity and overall resource requirements. Based on realistic parameters and commercially available electronics, our analysis demonstrates that a QCCD trapped-ion quantum computer with10,000trap electrodes can be controlled using only 13 field-programmable gate arrays and 104 high-speed DACs. This is in stark contrast to the10,000dedicated DACs required by conventional control methods. Consequently, employing this approach, we developed a proof-of-concept electronic system and evaluated its analog output performance.
Surface ion traps have lithographically defined electrode geometries that can be accurately simulated to calculate the voltages needed to store and transport ions, an enabling capability for trapped-ion quantum computing. While these voltage waveforms can be described explicitly as a voltage for each time step, they can be represented more compactly using cubic splines with coefficients calculated from the explicit target waveform. An FPGA would then calculate voltages on-the-fly based on these coefficients with a simple addition loop, sending these values as the input to digital-to-analog converters. Using cubic spline interpolation also increases the flexibility of the control system by simplifying the calibration offsets and time-scaling of waveforms without requiring additional explicit samples. In this paper we show that a single RF system-on-chip can be used to control 100 DAC channels, and propose a system-level architecture that uses scatter gather direct memory access and a highly compact custom data structure to store and generate voltage control waveforms in real-time.
Scalable trapped-ion quantum computing requires fast and reliable transport of ions through complex, segmented radiofrequency trap architectures without inducing excessive motional excitation. We present a numerical toolchain for the systematic generation of time-dependent electrode voltages enabling fast, low-excitation ion shuttling in segmented radiofrequency traps. Based on a model of the trap electrode geometry, the framework combines an electrostatic field solver, efficient unconstrained optimization, waveform postprocessing, and dynamical simulations of ion motion to compute voltage waveforms that realize prescribed transport trajectories while respecting experimental constraints such as voltage limits and bandwidth. The toolchain supports arbitrary trap geometries, including junctions and multi-zone layouts, and allows for the flexible incorporation of optimization objectives. We provide a detailed assessment of the accuracy of the framework by investigating its numerical stability and by comparing measured and predicted secular frequencies. The framework is optimized for numerical performance, enabling rapid numerical prototyping of trap architectures of increasing complexity. As application examples, we apply the framework to the transport of a potential well along a linear, uniformly segmented trap, and we compute a solution for shuttling a potential well around the corner of an X-type trap junction. The presented approach provides an extensible and highly efficient numerical foundation for designing and validating transport protocols in current and next-generation trapped-ion processors.