Superconducting Qubit TLS Scrambling With Targeted Light Pulses
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Solution Overview
Problem
Two-level systems (TLSs) cause significant decoherence in superconducting qubits, particularly on-resonant TLSs, leading to degraded gate fidelities and coherence times in quantum processors.
Innovation Solution
An iterative process of applying light pulses to scramble the frequencies of TLSs using laser illumination, measuring qubit relaxation times, and adjusting light pulses based on TLS configurations to minimize strong interactions, thereby improving coherence times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heating the entire quantum processor is used to mitigate TLS effects, then TLS frequencies are shifted off-resonant, but the process is time-consuming and non-targeted
Solution Approach 1:
The patent applies light pulses locally to specific qubits or regions of the quantum processor rather than heating the entire processor. This localized approach targets TLS interactions at specific locations, achieving the same coherence improvement much faster than global heating methods.
Solution Approach 2:
The patent replaces the thermal heating mechanism with optical excitation using light pulses. Instead of using thermal energy to shift TLS frequencies, the system uses resonant optical fields to directly interact with and scramble TLS states, achieving faster and more precise control.
2Reliability
If global light pulses are applied to the quantum processor, then TLS frequencies are scrambled across all qubits, but the process illuminates multiple qubits when only specific qubits need treatment
Solution Approach 1:
The patent implements spatially selective illumination where light pulses are directed only at specific qubits or regions requiring TLS mitigation. This is achieved through controlled delivery mechanisms that limit the spatial extent of optical excitation, preventing unnecessary illumination of other qubits and avoiding unwanted effects.
3Reliability
If iterative light pulse application is used to achieve acceptable TLS configurations, then qubit coherence is significantly improved, but the process requires multiple measurement and adjustment cycles
Solution Approach 1:
The patent employs an iterative feedback loop where qubit relaxation times are continuously measured and used to determine when additional light pulses are needed. The system monitors TLS configuration and adjusts light pulse application accordingly, stopping when acceptable coherence levels are achieved. This feedback mechanism automates the optimization process and reduces manual intervention.
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
The method rapidly improves qubit coherence by shifting TLS frequencies off-resonance, reducing decoherence effects and enhancing quantum processor performance.
Implementation Method 1
The light pulse is used to scramble the ensemble of TLSs coupled to 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 uses an iterative process of applying light pulses and examining qubit relaxation times to eliminate or minimize two-level system (TLS) interaction with qubits. The system applies a first light pulse to illuminate a quantum processor having one or more qubits. The system receives qubit relaxation times that are measured at different electric field frequencies after applying the first light pulse. The system applies a second light pulse to illuminate the quantum processor upon determining that the received qubit relaxation times indicates presence of a strongly coupled TLS in the quantum processor.