Phase Qubit Cell With Anti-Correlated Bias Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Phase qubits in quantum computing systems face challenges with coherence due to noise sensitivity in bias currents, limiting their operational spectrum and coherence times.
Innovation Solution
A system of coupled phase qubits with a common bias circuit that provides equal and opposite bias changes to each qubit, minimizing noise sensitivity by ensuring the derivative of the energy with respect to the supply current is zero, thereby reducing the impact of noise fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common bias circuit is used to bias multiple phase qubits, then device complexity is reduced, but noise sensitivity increases and coherence time decreases
Solution Approach 1:
The patent applies counterweight by providing equal and opposite bias currents to different qubits through the common bias circuit. When one qubit experiences a positive bias fluctuation, another qubit experiences an equal negative bias fluctuation, causing noise cancellation in the collective quantum state and extending coherence time despite using a simplified common bias circuit
2Measurement precision
If bias current is increased to improve signal strength, then measurement precision improves, but noise sensitivity increases and coherence time decreases
Solution Approach 1:
The patent converts the harmful noise effect of increased bias current into a beneficial signal by using differential measurement techniques. The equal and opposite biasing scheme ensures that noise affects all qubits similarly, allowing differential readout to cancel common-mode noise while preserving the signal, thus maintaining measurement precision without sacrificing coherence time
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
This approach enhances coherence times by reducing noise effects, allowing for improved stability and accuracy in quantum information storage and processing.
Implementation Method 1
A Josephson junction is a tunnel junction, made of two pieces of superconducting metal separated by a very thin insulating barrier, for example, about one nanometer in thickness. The insulating barrier is sufficiently thin to allow electrons, or in the superconducting state, Cooper-paired electrons, to tunnel through the barrier at an appreciable rate.
Implementation Method 2
a common bias circuit configured to provide a first bias to the first phase qubit and a second bias to the second phase qubit, such that a change in bias experienced by the first phase qubit is mirrored by an equal and opposite change in bias provided to the second phase qubit
Data Source
Figure 1~5
Figure 3~4
Figure 6
AI summary
Methods and apparatuses are provided for storing a quantum bit. One apparatus includes a first phase qubit, a second phase qubit, and a common bias circuit configured to provide a first bias to the first phase qubit and a second bias to the second phase qubit, such that noise within the first bias is anti-correlated to noise within the second bias.