Quantum Processing Apparatus with Downsampling ADC
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Solution Overview
Problem
Current quantum processing apparatuses face challenges in efficiently controlling and reading out a large number of solid-state qubits due to the need for numerous quantum chip inputs and outputs, radiofrequency lines, and frequent calibration of down-converters, which are hindered by temperature drift and high power dissipation.
Innovation Solution
A quantum processing apparatus equipped with downsampling analog-to-digital converters (DSADCs) that operate in higher Nyquist zones to down-convert analog signals from qubits to lower zones, reducing the number of required inputs and outputs, and incorporating a signal cancelation unit to minimize carrier amplitude, thereby reducing power dissipation and eliminating the need for dedicated mixers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual bias cables are used for each qubit to tune energy levels, then qubit frequency control is achieved, but the number of required connections and device complexity increases significantly
Solution Approach 1:
A single bias line is designed to serve multiple qubits simultaneously through frequency-selective coupling. The bias line can tune the energy levels of different qubits at different frequencies, allowing one connection to replace multiple individual bias cables. This multi-functional approach reduces the number of required connections while maintaining the ability to independently control each qubit's frequency.
Solution Approach 2:
The biasing function is segmented into frequency-specific control channels along a shared physical infrastructure. Instead of having separate physical cables for each qubit, the system segments the control signal into different frequency components that can be selectively applied to different qubits through resonant coupling, achieving independent control with shared infrastructure.
2Speed
If down-converters are used for signal conversion, then frequency conversion is achieved, but temperature drift requires frequent calibration
Solution Approach 1:
The readout circuitry is designed to be self-calibrating by using the qubit's own resonant frequency as a reference for the down-conversion process. The system automatically tracks and compensates for frequency drift by locking onto the qubit's natural resonance, eliminating the need for external calibration procedures and improving long-term stability.
Solution Approach 2:
The down-conversion frequency is dynamically adjusted to track the qubit's operating frequency, which itself is stabilized through careful design of the resonant circuit parameters. By making the conversion parameters dependent on the qubit's actual state rather than fixed values, the system automatically compensates for environmental drift without requiring external calibration.
3Measurement precision
If multiple ADCs are used for reading out qubits, then signal detection capability is improved, but power dissipation and device complexity increase
Solution Approach 1:
Multiple qubit readout signals are combined into a single transmission line that carries multiplexed information from multiple qubits to a single ADC. The signals are frequency-division multiplexed, allowing simultaneous readout of multiple qubits through one converter, thereby reducing the total number of ADCs required and lowering overall power consumption while maintaining detection precision.
Solution Approach 2:
A single ADC is designed to handle multiple input channels by implementing a multi-functional readout circuit that can sequentially or simultaneously process signals from different qubits. This universal readout approach allows one ADC to replace multiple dedicated converters, reducing power dissipation and device complexity while preserving the ability to detect signals from all qubits.
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 reduces thermal power, minimizes calibration requirements, and allows for real-time behavior improvement by placing control electronics closer to qubits, enhancing signal-to-noise ratio and reducing the complexity of clock synchronization, while maintaining efficient operation across a larger number of qubits.
Implementation Method 1
Each DSADC is configured to downsample analog signals obtained from the at least one of the M solid-state qubits. Such a DSADC operates in an nth Nyquist zone of the spectrum of the analog signals obtained, so as to down-convert such analog signals from the nth Nyquist zone to an mth Nyquist zone of the spectrum, where n>m≥1, prior to sampling the analog signals
Implementation Method 2
the control electronics further comprise a signal cancelation unit, or SCU, which includes an digital-to-analog converter, or DAC, wherein the SCU is connected to the at least one of the M solid-state qubits and the DSADC, so as to perform signal cancelation and thereby reduce a carrier amplitude of analog signals down-converted by the DSADC
Data Source
AI summary
Systems and methods directed to a quantum processing apparatus are provided. The apparatus comprises M solid-state qubits, where M>1, and control electronics, which are connected to the solid-state qubits. The control electronics comprise one or more qubit readout circuits, where each of the qubit readout circuits is connected to at least one of the solid-state qubits and comprises a downsampling analog-to-digital converter (hereafter DSADC). Each DSADC is configured to downsample analog signals obtained from the at least one of the solid-state qubits. Such a DSADC operates in the nth Nyquist zone of the spectrum of the analog signals obtained, so as to down-convert such analog signals from the nth Nyquist zone to the mth Nyquist zone of the spectrum, where n>m≥1, prior to sampling the analog signals to convert them into digital signals, in operation. One or more embodiments of the invention are further directed to a related method of operating such a quantum processing apparatus.