Superconducting Quantum Circuit for Intrinsic 2N-to-1 Photon Exchange

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Solution Overview

Problem

Existing superconducting quantum circuits require external time-varying excitations, such as parametric pumping techniques, to achieve non-linear conversion between modes, which leads to heating and reduced coherence times, destabilizing the quantum dynamics.

Innovation Solution

A non-linear superconducting quantum circuit that performs intrinsic 2N-to-1 photon exchange between modes by applying a predetermined current, eliminating the need for external excitations and enhancing coherence through internal resonant frequency matching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If external time-varying excitations (parametric pumping techniques) are applied to achieve non-linear conversion between modes, then the non-linear conversion is achieved, but heating occurs and coherence times are reduced

Engineering Contradiction:
Improvenon-linear conversion capabilityVSAvoidheating and reduced coherence times
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The circuit performs intrinsic non-linear conversion through its own design parameters (inductance ratio, coupling coefficient) rather than requiring external parametric pumping. The system serves itself by utilizing the natural resonant frequency relationship between modes enabled by the circuit topology, eliminating the need for external time-varying excitations that cause heating and coherence degradation

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the circuit parameters (inductance values L1, L2, coupling coefficient k) to achieve the desired non-linear conversion. By setting specific parameter relationships where the second resonant frequency is 2N times the first resonant frequency, the circuit inherently performs the non-linear conversion without external excitation, thus avoiding the harmful effects of parametric pumping

Inventive Principle:
Principle #35Parameter changes

2Productivity

If parametric pumping techniques are used for non-linear conversion, then mode conversion is achieved, but quantum dynamics stability is degraded

Engineering Contradiction:
Improvemode conversion efficiencyVSAvoidquantum dynamics stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The circuit achieves mode conversion through its intrinsic design rather than external parametric pumping. The quantum dynamics remain stable because the conversion is driven by the circuit's natural resonant properties and fixed parameter relationships, not by external time-varying excitations that destabilize the quantum state

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Instead of using external excitations to force mode conversion (conventional approach), the invention inverts the approach by designing the circuit parameters so that the circuit naturally and intrinsically performs the conversion. This reversal eliminates the destabilizing effect of external pumping on quantum dynamics

Inventive Principle:
Principle #13The other way round (Inversion)

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 circuit achieves a resonant 2N-to-1 photon exchange with improved coherence and stability, increasing the exchange rate by one or two orders of magnitude and enabling the stabilization of quantum manifolds for fault-tolerant quantum computation.

Implementation Method 1

the at least one loop includes one or more Josephson junctions, the circuit being configured to perform the resonant 2N-to-1 photon exchange when the predetermined current is applied so as to induce a phase difference across the one or more Josephson junctions

Methodology Applied
Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentEP4682778A1Non-linear superconducting quantum circuit
Publication Date: 2026.01.21 ALICE & BOB
  • EP4682778A1 patent drawingFigure 1~2e
  • EP4682778A1 patent drawingFigure 3a~4b
  • EP4682778A1 patent drawingFigure 5a~5d

AI summary

The disclosure notably relates to a non-linear superconducting quantum circuit having a first mode and a second mode. Each of the first mode and the second mode has a respective resonant frequency. The circuit is configured such that the resonant frequency of the second mode is substantially 2N times the resonant frequency of the first mode when a predetermined current of a constant intensity is applied to the circuit. The circuit thereby performs intrinsically a resonant 2N-to-1 photon exchange between respectively the first mode and the second mode, N being a positive integer. This forms an improved non-linear superconducting quantum circuit.