Driven Kerr Nonlinear Oscillator Using Detuned Drive for Qubit Coherence
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Solution Overview
Problem
Quantum computing faces challenges in maintaining qubit coherence due to decoherence from uncontrolled environmental interactions, particularly in noisy environments, which affect the stability and fidelity of quantum states in nonlinear oscillators.
Innovation Solution
A circuit quantum electrodynamics (cQED) system utilizing a Kerr nonlinear oscillator with reduced bare nonlinearity and detuned drive frequencies, specifically driven at ωp=2ωq+2Δ, where Δ is an integer multiple of −2K, to enhance coherence times and resilience against decoherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Kerr oscillator is driven at a frequency close to resonance (ωp ≈ 2ωq), then the oscillator responds strongly, but coherence time decreases due to enhanced decoherence from environmental interactions
Solution Approach 1:
The patent applies parameter changes by detuning the drive frequency from the resonant frequency. Specifically, the drive frequency ωp is set to 2ωq + 2Δ where Δ is an integer multiple of -2K, creating a controlled frequency offset that reduces decoherence while maintaining oscillator response through the nonlinear Kerr effect
2Measurement precision
If the drive amplitude is increased to improve signal strength, then measurement fidelity improves, but sensitivity to environmental noise and decoherence increases
Solution Approach 1:
The patent converts the harmful effect of environmental noise into a beneficial outcome by operating in a regime where the detuned drive frequency creates a protection mechanism. The nonlinear oscillator response at detuned frequencies naturally suppresses the impact of local noise while maintaining signal fidelity, effectively using the system's nonlinear properties to protect against decoherence
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 system achieves significantly longer coherence times and improved resilience to strong drive amplitudes, enabling robust operation of Kerr-cat qubits with high fidelity and reduced sensitivity to environmental noise.
Implementation Method 1
each of the plurality of SNAILS comprising a plurality of first Josephson junctions coupled in series and a second Josephson junction coupled in parallel with the plurality of first Josephson junctions
Implementation Method 2
wherein ωp=2ωq+2Δ, wherein Δ is an integer multiple of −2K, wherein K is a Kerr nonlinearity of the plurality of SNAILs of the Kerr oscillator
Data Source
AI summary
Techniques are describing for designing and operating a quantum oscillator. In contrast with conventional approaches to operating a quantum oscillator, the present techniques relate to an oscillator design that has less bare nonlinearity than is conventionally thought to be necessary for efficient operation. Moreover, the oscillator may be driven at a frequency that is detuned away from the frequency at which a nonlinear oscillator is typically driven. In particular, the detuned drive frequency may be substantially different from the typical drive frequency, and furthermore may be a frequency that may be expected to produce a low coherence time without also engineering the reduced nonlinearity described above. As a result, the combination of an engineered reduced nonlinearity combined with a detuned drive may result in a well behaved oscillator with a strong effective nonlinearity that exhibits significantly longer coherence times than conventional quantum oscillators.