Tunable Coupler Frequency Control for RF-Free Quantum Gates
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Solution Overview
Problem
Current quantum computing systems face challenges in efficiently performing quantum logic gates with high fidelity and scalability, particularly in implementing single-qubit and two-qubit gates without relying on radio frequency (RF) or microwave pulses, which can complicate system requirements and increase costs.
Innovation Solution
The use of a coupler device that applies direct current (DC) pulses to generate single-qubit phase gates or two-qubit controlled-phase gates, allowing for high-fidelity operations with tunable coupling and gate times, and enabling scalability by using qubits with fixed frequencies and couplers with adjustable operating frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio frequency (RF) or microwave pulses are used to perform quantum logic gates, then quantum logic gates can be implemented, but system requirements become complicated and costs increase
Solution Approach 1:
The patent extracts and eliminates the need for RF or microwave pulse generation hardware from the quantum computing system. By using a coupler device with adjustable operating frequency that can be tuned to match qubit frequencies, the system performs quantum logic gates through direct frequency matching rather than through RF/microwave pulses, thereby removing the complexity associated with pulse generation and control hardware
Solution Approach 2:
The patent changes the operating parameter of the coupler device from fixed frequency to adjustable frequency. By tuning the coupler's operating frequency to match the qubit frequency, the system enables direct interaction and quantum logic gate implementation without requiring external RF/microwave pulses, thus simplifying system requirements while maintaining gate fidelity
2Reliability
If RF or microwave pulses are used to perform quantum logic gates, then quantum logic gates can be implemented, but costs increase
Solution Approach 1:
The patent removes the need for expensive RF/microwave pulse generation equipment by using a tunable coupler device that naturally interacts with qubits through frequency matching. This extraction of unnecessary hardware directly reduces system costs while maintaining the ability to perform high-fidelity quantum logic gates
Solution Approach 2:
The patent employs a relatively simple and inexpensive coupler device with adjustable frequency capability instead of complex and costly RF/microwave generation systems. The coupler serves as a cost-effective intermediary that enables quantum logic operations without requiring expensive specialized hardware
3Duration of action of stationary object
If qubits with fixed frequencies are used, then coherence times are extended, but coupling control becomes more difficult
Solution Approach 1:
The patent introduces dynamic control at the coupler level rather than at the qubit level. By making the coupler's operating frequency adjustable while keeping qubit frequencies fixed, the system achieves dynamic coupling control without disturbing the qubits' stable frequency states, thereby preserving long coherence times while enabling versatile gate operations
Solution Approach 2:
The patent uses the coupler device as an intermediary between control signals and qubits. The coupler's adjustable frequency acts as a mediator that enables selective coupling to different qubits with fixed frequencies, providing coupling control versatility without requiring the qubits themselves to be tunable, thus maintaining their long coherence 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
This approach simplifies system requirements, reduces costs, and achieves high-fidelity quantum logic gates with short operation times and easy tunability, supporting scalable quantum computing architectures with long coherence times and high ON/OFF coupling ratios.
Implementation Method 1
in response to one or more coupler control signals received at a coupler device, a coupler operating frequency of the coupler device changes toward a qubit operating frequency of a qubit device
Implementation Method 2
a phase shift arises in a quantum state of the qubit device due to an interaction between the qubit device and the coupler device
Data Source
AI summary
In a general aspect, a quantum logic gate can be performed by tuning a coupler device. One or more coupler control signals can be received at a coupler device in a quantum processor cell. In some instances, in response to the coupler control signals, a coupler operating frequency of the coupler device changes toward a qubit operating frequency of a qubit device, and a phase shift arises in a quantum state of the qubit device due to an interaction between the qubit device and the coupler device. In some instances, in response to the control signals, the coupler operating frequency changes toward a first qubit operating frequency of a first qubit device, then changes toward a second qubit operating frequency of a second qubit device, and a controlled-phase shift arises in a quantum state of the qubit devices due to interactions between the coupler device and the respective qubit devices.