Qubit RF Pulse Multiplexing for Scalable State Change Control
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Solution Overview
Problem
The scalability of qubit circuit state change control systems is hindered by manufacturing tolerances and noise, leading to inaccuracy and reduced coherence time, particularly when using independent RF pulse generators for each qubit, which increases equipment costs and heat leak.
Innovation Solution
A combination of time domain multiplexing and frequency domain multiplexing is employed, using a single RF pulse generator for multiple qubits, with frequency selective filters and amplitude/phase adapters to compensate for manufacturing differences, allowing for simultaneous state changes across multiple qubits without the need for exact qubit matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If independent RF pulse generators are used for each qubit, then state change accuracy is improved, but equipment cost and heat leak increase
Solution Approach 1:
Multiple RF pulse generators are merged into a single shared generator. The patent combines the functionality of multiple independent RF pulse generators into one device that serves all qubits, thereby reducing equipment cost and heat leak while maintaining state change accuracy through alternative control mechanisms.
Solution Approach 2:
A signal multiplexer is introduced as an intermediary component between the shared RF pulse generator and multiple qubits. This multiplexer enables precise control of RF signal distribution to different qubits, compensating for the loss of independent generator control and maintaining measurement precision.
2Measurement precision
If independent RF pulse generators are used for each qubit, then state change accuracy is improved, but heat leak increases
Solution Approach 1:
Multiple RF pulse generators are merged into a single shared generator, directly reducing the number of heat-generating devices in the system. This consolidation significantly decreases heat leak to the qubits while maintaining operational precision through the multiplexer-based control architecture.
3Device complexity
If a single RF pulse generator is shared among multiple qubits, then equipment cost and heat leak are reduced, but state change accuracy deteriorates due to manufacturing tolerances
Solution Approach 1:
A signal multiplexer acts as an intermediary that provides precise control over RF signal distribution to each qubit. This intermediary component compensates for manufacturing tolerances by enabling accurate amplitude and phase control of RF pulses delivered to individual qubits from the shared generator.
Solution Approach 2:
The system dynamically adjusts RF signal parameters (amplitude, phase, timing) through the multiplexer based on which qubit is being addressed. This dynamic control capability ensures precise state changes for each qubit despite using a shared generator, overcoming static manufacturing variations.
4Device complexity
If time domain multiplexing is used to share RF pulse generators, then equipment cost is reduced, but coherence time is reduced due to pulse timing constraints
Solution Approach 1:
The signal multiplexer serves as an intermediary that enables rapid, precise switching between qubits with minimal transition time. This fast switching capability reduces the time qubits spend in vulnerable states during pulse transitions, thereby preserving coherence time while enabling cost-effective shared generator architecture.
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 state changes for a large number of qubits with reduced equipment costs and heat leak, maintaining coherence time by using shared RF pulse generators and adaptive amplitude/phase compensation.
Implementation Method 1
The frequency selective filter is configured to transmit a signal at a frequency corresponding to a resonance frequency of the qubit circuit
Implementation Method 2
The frequency of the RF signal in the pulse is related to the resonance frequency of the qubit and may be in the Gigahertz range
Implementation Method 3
the RF pulse to generate a superimposed electromagnetic field on a field in part of the superconducting resonant RF circuit
Implementation Method 4
a Josephson junction in this structure
Data Source
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AI summary
A qubit system is provided wherein successive sets of M RF pulses are generated simultaneously, for application to qubit circuits in a plurality of N groups of M qubit circuits. M switching multiplexer circuits are used, each to pass a respective one of the M RF pulses in the set to a selected one of a plurality of N M to one RF combiners in a multiplexing mode. Combined RF pulses at M different RF frequencies are transmitted from each of the N combiners to a transmission structure for a respective one of the groups. Individual ones of the combined RF pulses are coupled from the transmission structure for the group to respective ones of the qubit circuits of the groups via respective frequency selective filters. In a broadcast mode the M switching multiplexer circuits are used to transmit the simultaneous pulses to all of RF combiners.