Multipartite Qubit Entanglement Verification via Bell Inequality Testing
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Solution Overview
Problem
Existing methods for generating and verifying quantum-entangled qubits, such as Bell State measurements, are not always successful and can destroy the quantum state during verification processes, making it difficult to provide a reliable stream of entangled qubits for quantum technologies like QKD and distributed quantum computing.
Innovation Solution
A method involving performing a Bell State measurement on qubits from multi-partite quantum-entangled states and a Bell Inequality test on additional qubits to determine entanglement without destroying the quantum state, using a combination of beam splitters and single-photon detectors to verify entanglement between qubits across nodes in a telecommunications network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Bell State measurement is performed on two qubits to generate entanglement, then entangled qubits are produced, but the measurement is not always successful and destroys the quantum state
Solution Approach 1:
The patent divides the quantum system into multiple independent multipartite entangled states (e.g., three or more qubits per state), allowing the Bell State measurement to operate on one pair while leaving other qubits in the same state intact for verification purposes. This segmentation enables parallel operations without mutual interference.
Solution Approach 2:
The patent extracts the verification function from the original quantum state by using additional qubits within the multipartite structure that are not subjected to the Bell State measurement. These extracted qubits serve solely for verification, separating the measurement process from the state verification process.
2Measurement precision
If a Bell Inequality test is performed to verify entanglement, then verification is achieved, but the quantum state is destroyed in the process
Solution Approach 1:
The patent performs the Bell Inequality test on qubits that have already been involved in a successful Bell State measurement. The preliminary entanglement generation creates a verified entangled state that can then be tested without risking the loss of previously generated entanglement, as the test is performed on redundant qubits within the multipartite structure.
Solution Approach 2:
The patent uses intermediate qubits within the multipartite entangled state that act as mediators between the Bell State measurement process and the Bell Inequality verification. These intermediary qubits transfer the entanglement property without being directly subjected to both measurement and verification processes simultaneously.
3Reliability
If multiple qubits are used in multipartite states to enable verification without destruction, then the system complexity increases
Solution Approach 1:
The patent designs multipartite quantum states where each qubit serves multiple functions: some qubits participate in Bell State measurements, others are reserved for Bell Inequality tests, and all qubits collectively maintain the entangled state. This multi-functionality allows a single quantum system to perform both generation and verification operations without requiring separate systems.
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 method ensures the verification of entanglement between qubits without destroying the quantum state, providing a reliable stream of entangled qubits for quantum communication protocols, including QKD, by using Bell State measurements and Inequality tests across multiple iterations and nodes.
Implementation Method 1
The Bell State measurement may comprise mixing the first qubit with the second qubit. This may comprise passing the first and second qubits through a mixing beam splitter
Implementation Method 2
measuring may be performed with single-photon detectors. If a photon from one of the split outputs from each of the two Bell Inequality tests are detected, this may indicate that the Bell Inequality has been violated
Data Source
AI summary
There is herein provided a method of determining whether one or more pairs of qubits are quantum-entangled, the method comprising: performing a Bell State measurement on a first qubit, the first qubit being from a first multi-partite quantum-entangled state and a second qubit, the second qubit being from a second multi-partite quantum-entangled state, performing a Bell Inequality test on a third qubit, the third qubit being from the first multipartite quantum-entangled state and a fourth qubit, the fourth qubit being from the second quantum-entangled state, determining, using an outcome of the Bell Inequality test, whether a fifth qubit, the fifth qubit being from the first multipartite quantum-entangled state is quantum-entangled with a sixth qubit, the sixth qubit being from the second multi-partite quantum-entangled state.