Josephson Parametric Oscillator Filtering for Low-Loss Readout
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Solution Overview
Problem
Distributed constant-type nonlinear oscillators occupy a large area, making them unsuitable for integration in quantum computers, and existing methods for lumped constant-type oscillators do not effectively reduce loss or facilitate easy state reading.
Innovation Solution
A lumped constant-type oscillator with a resonator and magnetic-field generating means, connected through a filter, allowing for parametric oscillation and controlled frequency transmission to reduce loss and enable easy state reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If distributed constant-type nonlinear oscillators are used, then the loss of the fundamental mode can be reduced, but the oscillator occupies a large area making integration difficult
Solution Approach 1:
The patent applies dynamics by making the coupling between the resonator and read-out unit variable through a tunable filter. The filter's transmission characteristics can be dynamically adjusted to allow or block the fundamental mode based on operational requirements, enabling the system to switch between low-loss operation and readable operation states.
Solution Approach 2:
The patent changes the transmission parameter of the filter between two states: blocking the fundamental mode (for low loss) and transmitting the fundamental mode (for reading). This parameter change resolves the contradiction by allowing the system to achieve both low loss and readability at different times rather than simultaneously.
2Loss of information
If the coupling between the nonlinear oscillator and the read-out unit is made strong, then the energy transmitted to the read-out unit increases enabling reading-out, but the loss of the nonlinear oscillator increases causing performance deterioration
Solution Approach 1:
The patent makes the coupling strength dynamic by using a tunable filter whose transmission characteristics can be adjusted. When reading is required, the filter is tuned to transmit the fundamental mode, enabling strong coupling and reading. When reading is not required, the filter blocks the fundamental mode, reducing coupling and loss. This dynamic adjustment resolves the contradiction between reading capability and loss reduction.
Solution Approach 2:
The system operates in periodic cycles: during calculation phases, the filter blocks the fundamental mode to minimize loss; during readout phases, the filter transmits the fundamental mode to enable reading. This periodic switching between blocking and transmitting states allows the system to achieve both low loss during operation and readable output when needed.
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 solution reduces loss and allows for easy state reading of the oscillator, while occupying a smaller area, suitable for integration in quantum computers.
Implementation Method 1
a first Josephson junction, a second Josephson junction connected in a ring shape
Implementation Method 2
a 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
Implementation Method 3
a filter configured to restrict transmission of a signal in a predetermined frequency band
Implementation Method 4
magnetic-field generating means configured to apply a magnetic field to the loop circuit, and the oscillator being configured to perform parametric oscillation
Data Source
AI summary
An oscillation apparatus includes: an oscillator including a resonator and a magnetic-field generating 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 generating 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 filter configured to restrict transmission of a signal in a predetermined frequency band. A circuit in which the capacitor and the loop circuit are connected in a ring shape is connected to the read-out unit through the filter.