Variable-Coupled Quantum Oscillator for Low-Loss State Readout
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Solution Overview
Problem
The distributed constant-type nonlinear oscillators used in quantum computers occupy a large area, making them unsuitable for integration in practical quantum computers. Additionally, these oscillators have higher modes that cannot be applied to lumped constant-type nonlinear oscillators, which lack higher modes and face challenges in reducing loss and reading out their state effectively.
Innovation Solution
A lumped constant-type nonlinear oscillator is designed with a resonator that includes a loop circuit and a capacitor, connected in a ring shape. This oscillator features a magnetic-field generating means to apply a magnetic field to the loop circuit, enabling parametric oscillation. A variable coupling strength between the oscillator and the read-out means is achieved through a circuit component, allowing for reduced loss during quantum calculation and easy state reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If distributed constant-type nonlinear oscillators are used, then loss can be reduced, but the circuit occupies a large area making integration difficult
Solution Approach 1:
The patent changes the fundamental parameters of the oscillator design from distributed constant-type to lumped constant-type, while introducing a variable coupling mechanism that dynamically adjusts the coupling strength between the resonator and read-out line. This parameter change allows the system to achieve low loss without requiring the large waveguide structures of distributed constant-type oscillators.
Solution Approach 2:
The patent introduces a variable coupling mechanism that dynamically adjusts the coupling strength between the resonator and read-out line based on operational requirements. The coupling strength can be changed from strong (for reading out) to weak (for reducing loss during operation), allowing the system to adapt to different operational states and resolve the contradiction between loss reduction and compact size.
2Ease of operation
If coupling between nonlinear oscillator and read-out unit is made strong, then reading out becomes easy, but loss of the nonlinear oscillator increases
Solution Approach 1:
The patent introduces a variable coupling mechanism that dynamically adjusts the coupling strength between the resonator and read-out line based on operational requirements. The coupling strength can be changed from strong (for reading out) to weak (for reducing loss during operation), allowing the system to adapt to different operational states and resolve the contradiction between loss reduction and compact size.
Solution Approach 2:
The patent employs periodic switching of the coupling strength between the resonator and read-out line. During quantum computation, the coupling is weakened to minimize loss, and during read-out operations, the coupling is strengthened to facilitate state measurement. This periodic action allows the system to achieve both low loss and easy reading out at different times.
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 proposed solution reduces the loss of the nonlinear oscillator during quantum calculation and facilitates easy reading out of its state, while also minimizing the circuit area, making it suitable for integration in practical quantum computers.
Implementation Method 1
a first Josephson junction, a second Josephson junction connected in a ring shape
Implementation Method 2
magnetic-field generating means configured to apply a magnetic field to the loop circuit, enabling parametric oscillation
Implementation Method 3
the resonator including a loop circuit and a capacitor
Data Source
AI summary
An oscillation apparatus includes: an oscillator including a resonator and a magnetic-field generation unit, the resonator including a loop circuit and a capacitor, the loop circuit including a first superconducting line, a first Josephson junction, a second superconducting line, and a second Josephson junction connected in a ring shape, the magnetic-field generation unit being configured to apply a magnetic field to the loop circuit, and the oscillator being configured to perform parametric oscillation; a read-out unit for reading out an internal state of the oscillator; and a circuit component in which a coupling strength between the oscillator and the read-out unit is variable. The oscillator is connected to the read-out unit through the circuit component.