Pulse variational quantum eigensolver on cross-resonance based hardware

State-of-the-art noisy digital quantum computers can only execute short-depth quantum circuits. Variational algorithms are a promising route to unlock the potential of noisy quantum computers since the depth of the corresponding circuits can be kept well below hardware-imposed limits. Typically, the variational parameters correspond to virtual $R_Z$ gate angles, implemented by phase changes of calibrated pulses. By encoding the variational parameters directly as hardware pulse amplitudes and durations we succeed in further shortening the pulse schedule and overall circuit duration. This decreases the impact of qubit decoherence and gate noise. As a demonstration, we apply our pulse-based variational algorithm to the calculation of the ground state of different hydrogen-based molecules (H$_2$, H$_3$ and H$_4$) using IBM cross-resonance-based hardware. We observe a reduction in schedule duration of up to $5\times$ compared to CNOT-based Ans\"atze, while also reducing the measured energy. In particular, we observe a sizable improvement of the minimal energy configuration of H$_3$ compared to a CNOT-based variational form. Finally, we discuss possible future developments including error mitigation schemes and schedule optimizations, which will enable further improvements of our approach paving the way towards the simulation of larger systems on noisy quantum devices

Framework for Automatic PCB Marking Detection and Recognition for Hardware Assurance

A Bill of Materials (BoM) is a list of all components on a printed circuit board (PCB). Since BoMs are useful for hardware assurance, automatic BoM extraction (AutoBoM) is of great interest to the government and electronics industry. To achieve a high-accuracy AutoBoM process, domain knowledge of PCB text and logos must be utilized. In this study, we discuss the challenges associated with automatic PCB marking extraction and propose 1) a plan for collecting salient PCB marking data, and 2) a framework for incorporating this data for automatic PCB assurance. Given the proposed dataset plan and framework, subsequent future work, implications, and open research possibilities are detailed.Comment: 5 pages, 3 figures, Government Microcircuit Applications & Critical Technology Conference (GOMACTech) 202

Open-Loop Electrowetting Actuation with Micro-Stepping

Microfluidic-driven mechanical actuation opens new possibilities for positioning and manipulating delicate small components. However, existing microfluidic actuation methods are not well-suited to positioning with high resolution. This paper reports a method for precise, open-loop control of droplet position in finite steps by varying the duty cycle of the input signal in electrowetting actuation. When wetted to a solid object, both the droplet and the solid can be actuated. Unlike conventional electrowetting actuation methods, positioning resolution in our proposed method can be much smaller than the size of the underlying electrodes without requiring closed loop feedback control system. Using a leaky dielectric coating, the electrode/electrolyte combination in our device acts as a simple diode by blocking current in one direction and conducting in the other. Each duty cycle of the applied AC square wave corresponds to a unique position on the electrode. The position – duty cycle relationship is found to be nonlinear but symmetric about the center of the electrodes. This approach provides a method for improving open-loop positioning resolution without adding more electrodes. Positioning is within 0.2 mm ( \u3c 2.5% of the droplet diameter) of the idealized model and repeatability is \u3c 0.07 mm ( \u3c 0.8% of the droplet diameter)

Robust Bidirectional Continuous Electrowetting Based on Metal–Semiconductor (M–S) Diodes

We demonstrate bidirectional continuous electrowetting by embedding metal–semiconductor diodes in the electrowetting substrate. Unlike conventional electrowetting on dielectric, bidirectional continuous electrowetting uses a single electrode pair to actuate a droplet through long distances. As long as the voltage potential is maintained between two end electrodes, the droplet moves toward the electrode with the higher potential. However, previously reported material systems had limited success in repeated actuation. In this work, diodes based on Schottky barriers were fabricated by forming metal–semiconductor junctions between titanium and high-resistivity n-type silicon. The performance enhancements were evaluated using current–voltage measurements of interface pairs. When the titanium is coated with gold to limit electrochemical reactions, the Schottky diodes achieved superior performance compared to electrochemical diodes previously studied. Droplet speed range from 8 to 240 mm/s is reported. Under repeated actuation, the speed of the droplet showed no degradation for up to 2000 cycles (experiment duration)

Electrowetting Force and Velocity Dependence on Fluid Surface Energy

Electrowetting on dielectric is a phenomenon in which the shape and apparent contact angle of a droplet changes when an electric field is applied across the droplet interface. If the field is asymmetric with respect to the droplet, then a net force can be applied to the droplet. In this work, we have measured the electrowetting force by confining the droplet shape beneath a glass plate and measuring the force on the plate. The force was measured as a function of voltage for a range of fluids with different surface energy. Measured forces show excellent agreement with predictions based on the Young–Lippmann equation with measured contact angles. Results also show that the electrowetting force is independent of fluid surface energy below saturation but that the peak force is proportional to the surface tension. This work shows that lowering the surface energy of the fluid can induce larger contact angle change under the same voltage, but it has no beneficial impact on the actuation force in droplet-based actuators. In contrast, velocity tests with deformable droplets show higher speeds for lower surface energy fluids, even above their saturation voltage. However, when the droplet’s shape is restrained, the highest velocity is achieved with high surface energy fluids due to the larger electrowetting actuation forces applied