Bandpass-Filtered Qubit Optical Tuning for TLS Decoherence Mitigation
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Solution Overview
Problem
Two-level systems (TLS) cause significant decoherence in superconducting quantum circuits, particularly on-resonant TLSs, leading to degraded gate fidelities in quantum processors, which existing methods like global heating are inefficient and stochastic.
Innovation Solution
A quantum processor system using light pulses to scramble TLS frequencies, employing bandpass filters and optical fibers to selectively target and tune wavelengths to individual qubits, allowing rapid frequency shifting of TLSs to off-resonant states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If global heating is used to mitigate TLS effects, then TLS frequencies are shifted off-resonant, but the process is time-consuming and affects the entire quantum processor
Solution Approach 1:
The patent divides the quantum processor into individual qubit units, each with its own dedicated laser source and optical path. This segmentation allows selective addressing of specific qubits experiencing TLS decoherence without affecting the entire processor, enabling rapid targeted mitigation rather than global heating of all qubits simultaneously.
Solution Approach 2:
The patent implements local quality by providing each qubit with customized optical filtering characteristics. Bandpass filters are selectively applied to individual qubit paths to pass only the specific wavelengths that resonate with TLS frequencies affecting that particular qubit. This localized approach optimizes mitigation effectiveness for each qubit while minimizing impact on others.
2Measurement precision
If bandpass filters are used to selectively target individual qubits, then mitigation precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces optical bandpass filters as intermediary components between the laser sources and qubits. These filters act as mediators that selectively transmit only the specific wavelengths corresponding to TLS frequencies for each qubit, enabling precise targeting without requiring complex wavelength tuning mechanisms at each qubit location.
Solution Approach 2:
The patent employs a modular optical architecture where each qubit receives light through a dedicated optical path with its own bandpass filter. This copying approach replicates the basic laser-filter-qubit unit for each qubit, simplifying the overall system design compared to shared optical paths while maintaining individualized mitigation precision.
3Ease of manufacture
If fixed frequency qubits are used, then processor design is simplified, but on-resonant TLS have significant detrimental effect on gate fidelities
Solution Approach 1:
The patent converts the harmful resonant interaction between fixed-frequency qubits and TLS into a beneficial effect. By using bandpass filters to pass specific wavelengths that match TLS frequencies, the system exploits the resonant coupling to detect and mitigate TLS effects, transforming what was previously a source of decoherence into a diagnostic and corrective mechanism.
Solution Approach 2:
The patent changes the optical parameters (wavelength, bandwidth) of the mitigation system to match the specific TLS frequencies affecting each qubit. The bandpass filters are configured with center frequencies and bandwidths optimized for the TLS spectrum, allowing selective mitigation of resonant interactions while maintaining fixed qubit operating frequencies.
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
Improves qubit coherence times and maintains stable quantum processor performance by rapidly shifting TLS frequencies, reducing decoherence effects, and optimizing qubit performance without global heating processes.
Implementation Method 1
An array of bandpass filters is provided, with each bandpass filter aligned with a qubit on the quantum processor and tuned to pass a unique range of wavelengths
Implementation Method 2
The light pulses are used to scramble strongly coupled two-level systems (TLS) in the quantum processor
Data Source
AI summary
Methods and systems for mitigating the effects of defects in a quantum processor are provided. A mitigation system includes a quantum processor comprising a plurality of qubits. The system includes a light emitting source that can be tuned to produce light pulses of different wavelengths. The system includes an array of bandpass filters. Each bandpass filter is aligned with a qubit on the quantum processor and has a unique pass band. The system may include a controller configured to receive a selection of a qubit and to tune the light emitting source to emit a light pulse having a wavelength that falls within a range of a bandpass filter that is aligned with the selected qubit. The light pulse is used to scramble an ensemble of strongly coupled two-level system (TLS) in the processor.