Multiplexed DAC Offset Circuits for Ion Trap Electrode Control
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Solution Overview
Problem
In trapped ion quantum computing (TIQC) systems, controlling hundreds or thousands of electrodes simultaneously to provide precise electric fields is challenging due to high cost and power requirements, and stray electric fields cause excess micromotion and heating, necessitating advanced techniques for efficient DAC-to-electrode connections and DC offset voltage application.
Innovation Solution
The use of multiplexed digital-to-analog converters (DACs) with DC offset circuits, where DC offset voltages are added to outputs of multiplexed DACs to compensate stray electric fields, allowing for configurable DC offset compensation, reducing the need for high-resolution DACs and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hundreds or thousands of DACs are used to control each electrode individually, then precise control of electric fields is improved, but cost and device complexity increase significantly
Solution Approach 1:
Multiple DAC outputs are combined through a summing circuit to generate the control voltage for a single electrode. This merging approach allows multiple digital-to-analog converter channels to be aggregated, reducing the total number of DACs required while maintaining precise voltage control capability through the superposition of multiple voltage signals.
Solution Approach 2:
A single DAC channel is designed to serve multiple electrodes by time-multiplexing its output. The DAC output is routed to different electrodes at different times through switching circuitry, allowing one DAC to perform the function of multiple DACs would otherwise be needed, thereby reducing overall system complexity and cost.
2Measurement precision
If high-resolution DACs are used to compensate for stray electric fields, then control precision is improved, but power consumption increases
Solution Approach 1:
Instead of using high-resolution DACs that provide excessive precision, the system uses lower-resolution DACs with added DC offset voltages to achieve the necessary compensation precision. This partial action approach applies just enough correction to eliminate stray fields without the overhead of high-resolution conversion, reducing power consumption while maintaining adequate performance.
Solution Approach 2:
The system changes the voltage parameter by adding configurable DC offset voltages to the DAC outputs. This parameter modification allows the system to compensate for stray electric fields by shifting the voltage baseline rather than relying solely on high-resolution DAC precision, thereby achieving field compensation with lower-power, lower-resolution converters.
3Reliability
If DC offset circuits are added to each electrode, then stray field compensation capability is improved, but device complexity increases
Solution Approach 1:
Multiple DC offset voltage generation functions are merged into shared circuitry that serves multiple electrodes. Rather than implementing separate DC offset circuits for each electrode, the system uses a common offset generation and distribution network that can programmatically apply appropriate offsets to different electrodes, reducing component count while maintaining individualized compensation capability.
Solution Approach 2:
A central control unit acts as an intermediary between the digital control system and the electrode DC offset circuits. This mediator translates digital offset commands into analog voltage adjustments and distributes them appropriately, coordinating the operation of multiple DC offset circuits without requiring each electrode to have independent control logic, thereby managing complexity through centralized coordination.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient control of ion movement with reduced power and cost, while maintaining precise control over electric fields, thereby improving the stability and performance of TIQC systems.
Implementation Method 1
a first DC offset circuit coupled between the first output and the first electrode, the first DC offset circuit configured to add a first DC offset voltage to either the first voltage or the first voltage amplified by a first gain
Implementation Method 2
a multiplexer having multiple inputs and multiple outputs, the multiple inputs coupled to the plurality of DACs, the multiple outputs including a first output configured to provide a first voltage
Implementation Method 3
electrostatic potentials are used to move ions between storage and processing locations in a process called ion shuttling
Implementation Method 4
converting, by the plurality of DACs, multiple digital voltage values to multiple analog voltages
Data Source
Figure 1
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Figure 3A
AI summary
A device includes a plurality of digital-to-analog converters (DACs), a multiplexer, a plurality of electrodes including a first electrode, and a plurality of direct current (DC) offset circuits including a first DC offset circuit. At least one of the plurality of electrodes is located along a lane for movement of an ion. The multiplexer has multiple inputs coupled to the plurality of DACs and multiple outputs including a first output. The first output is configured to provide a first voltage. The first DC offset circuit is coupled between the first output and the first electrode. The first DC offset circuit is configured to add a first DC offset voltage to either the first voltage or the first voltage amplified by a first gain. The first DC offset voltage is configurable. Significant Figure: [Fig. 4]