Photonic Quantum Memory Using Time-Bin Entanglement Conversion
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Solution Overview
Problem
Current photonic quantum memory systems face challenges in preserving entanglement and coherence of quantum states, particularly due to birefringence-induced degradation of polarization-entangled photon pairs in fiber storage, which limits their storage lifetime and degrades quantum information.
Innovation Solution
The development of a photonic quantum memory system that utilizes time-bin entangled photons, which are less affected by birefringence, allowing for the storage and retrieval of entangled photon pairs with minimal absorption losses and phase changes, using modules for entanglement conversion between polarization and time-bin bases, ensuring entanglement preservation and compatibility with quantum computing units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarization-entangled photon pairs are stored in fiber, then quantum information can be preserved, but birefringence degrades the entanglement and limits storage lifetime
Solution Approach 1:
The patent transforms the entanglement basis from polarization to time-bin encoding. This parameter change in the quantum state representation makes the stored photons immune to birefringence effects, as time-bin entanglement does not suffer from polarization-dependent phase shifts. The conversion is achieved using interferometric devices that map polarization entanglement to time-bin entanglement, thereby extending storage lifetime while maintaining entanglement fidelity.
2Adaptability or versatility
If polarization entanglement is used, then quantum computation can be performed, but birefringence introduces phase changes that degrade the quantum state
Solution Approach 1:
The patent introduces time-bin encoding as an intermediary representation for storing quantum states. Instead of directly storing polarization entanglement which is vulnerable to birefringence, the system uses time-bin entanglement as a stable intermediate form that can be later converted back to polarization entanglement for quantum computation. This intermediary approach decouples the storage stability requirement from the computation compatibility requirement.
Solution Approach 2:
The system performs parameter transformation between polarization basis and time-bin basis. During storage, quantum states are represented in the time-bin parameter space which is stable against birefringence. When retrieval is needed for quantum computation, the parameter space is transformed back to polarization basis, maintaining both stability during storage and compatibility with quantum gates.
3Duration of action of stationary object
If photons are stored in fiber for extended periods, then quantum memory function is achieved, but absorption losses increase and reduce the quality of stored photons
Solution Approach 1:
By changing the encoding parameter from polarization to time-bin, the system enables longer storage durations without exponential degradation from absorption losses. Time-bin entangled photons can be stored in fiber loops with circulators and optical switches that maintain the quantum state while allowing for controlled retrieval, effectively managing the trade-off between storage duration and absorption losses.
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 enables longer entanglement maintenance of time-bin entangled photon pairs, enhancing the storage lifetime and preserving quantum information integrity, thus supporting universal quantum computation with reduced errors.
Implementation Method 1
The development of a photonic quantum memory system that utilizes time-bin entangled photons, which are less affected by birefringence
Implementation Method 2
modules for entanglement conversion between polarization and time-bin bases
Implementation Method 3
modules for entanglement conversion between polarization and time-bin bases
Implementation Method 4
time-bin entangled photons, which are less affected by birefringence, allowing for the storage and retrieval of entangled photon pairs with minimal absorption losses and phase changes
Data Source
AI summary
A photonic quantum memory is provided. The photonic quantum memory includes entanglement basis conversion module configured to receive a first polarization-entangled photon pair and to produce a second entangled photon pair. The second polarization-entangled photon pair can be a time-bin entangled or a propagation direction-entangled photon pair. The photonic quantum memory further includes a photonic storage configured to receive the second entangled photon pair from the basis conversion module and to store the second entangled photon pair.