Galvanically Coupled ATS Quantum Circuit for Cat Qubit Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing superconducting quantum circuits with cat qubits face challenges in achieving a high enough ratio of confinement rate to phase-flip rate, leading to insufficient bit-flip stabilization times, which are crucial for practical quantum computing applications.
Innovation Solution
A non-linear superconducting quantum circuit with an asymmetrical threaded superconducting quantum interference device (ATS) connected galvanically, featuring a first and second mode with distinct resonant frequencies, and a minimal component design to enhance the 2-to-1 photon conversion rate, minimizing noise and loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transmon is used to engineer 2-to-1 photon conversion, then the stabilization scheme can be implemented, but spurious cross-Kerr terms induce additional noise processes with high escape rates
Solution Approach 1:
The patent removes the transmon component from the circuit entirely, extracting the source of spurious cross-Kerr terms and noise processes. By using only an ATS device for 2-to-1 photon conversion without an additional transmon, the harmful noise processes with high escape rates are eliminated while maintaining the stabilization function.
Solution Approach 2:
The patent uses a minimal circuit configuration with only essential components (ATS device, resonant portion, and coupling capacitor) rather than complex multi-component designs. This simplified approach uses 'cheaper' (simpler) components that introduce fewer noise processes, achieving stabilization without the expensive complexity of transmon-based designs.
2Ease of operation
If a transmon is used to measure the cat qubit state, then measurement is enabled, but the bit-flip time saturates to a few milliseconds
Solution Approach 1:
The patent removes the measuring transmon from the circuit, extracting the source of bit-flip time saturation. By eliminating this component entirely, the harmful saturation effect is removed while measurement capability is preserved through alternative means (coupling to external measurement apparatus).
Solution Approach 2:
The patent uses a coupling capacitor as an intermediary element to enable measurement without direct transmon involvement. The capacitor provides the necessary coupling between the ATS device and external measurement apparatus, allowing measurement functionality while preventing the bit-flip time saturation caused by direct transmon measurement.
3Duration of action of moving object
If the ATS is operated in a regime where it is dynamically stable, then bit-flip time increases to 100 seconds, but the confinement rate becomes very low
Solution Approach 1:
The patent optimizes the parameters of the ATS device and circuit configuration to achieve both high confinement rate and long bit-flip time. By carefully selecting the ATS parameters, resonant frequency ratios, and coupling capacitor values, the system operates in a regime that simultaneously provides strong confinement (high rate) and long stabilization time, resolving the trade-off between speed and duration.
4Reliability
If the ratio of confinement rate to phase-flip rate is increased to 10^4, then quantum error correction performance improves, but current implementations achieve only ratios of 10 or 0.01
Solution Approach 1:
The patent employs comprehensive parameter optimization across multiple variables: ATS device characteristics, resonant frequency ratios between modes, coupling capacitor values, and operating conditions. This multi-parameter tuning enables the system to achieve the target ratio of 10^4 or higher, dramatically improving quantum error correction performance compared to previous implementations.
Solution Approach 2:
The patent uses a composite circuit architecture combining the ATS device with a specifically designed resonant portion and coupling elements. This composite structure leverages the complementary strengths of each component to achieve both high confinement rate and long bit-flip time, enabling the required ratio for effective quantum error correction.
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 design significantly increases the 2-to-1 photon conversion rate, achieving bit-flip stabilization times up to 100 seconds, surpassing previous implementations by several orders of magnitude, while maintaining low phase-flip rates.
Implementation Method 1
The dissipative stabilization of two coherent states utilizes an engineering of a non-linear conversion between two photons of a first mode that hosts the stabilized quantum manifold
Implementation Method 2
an asymmetrical threaded superconducting quantum interference device (also referred to as 'ATS') to engineer the 2-to-1 photon conversion
Implementation Method 3
said non-linear superconducting quantum circuit has zero-point fluctuations of the superconducting phase across the asymmetrical threaded superconducting quantum interference device for the first mode and the second mode
Implementation Method 4
a non-linear superconducting quantum circuit which comprises at least one resonant portion and an asymmetrical threaded superconducting quantum interference device connected galvanically
Data Source
AI summary
A non-linear superconducting quantum circuit (circuit) comprises a resonant portion and an asymmetrical threaded superconducting quantum interference device (ATS), connected galvanically, and which implements first and second modes with respective resonant frequencies, wherein the ratio between the resonant frequencies is different by 1/2. The resonant portion has a symbolic representation comprising a linear resonant portion implemented with an inductor and a capacitor, and a non-linear resonant portion implemented with a capacitor and the ATS, wherein the linear and non-linear resonant portions are connected galvanically and are arranged such that one has elements connected in series, and the other has elements connected in parallel. The resonant portion is configured with inductance and capacitance values which induce, with the ATS, the first and second modes such that the circuit has zero-point fluctuations of the superconducting phase across the ATS for the first and second modes at or above 0.05 rad.