Fiber-Coupled Time-Bin Teleportation for 22 Km Quantum Links
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Solution Overview
Problem
Existing quantum teleportation systems for telecom-band photonic time-bin qubits achieve fidelity below 90% and lack forward compatibility with emerging quantum devices for the quantum Internet, particularly using practical devices that allow straightforward replication and deployment.
Innovation Solution
A quantum teleportation system comprising a transmitter, source of entangled photons, coupler, detectors, receiver, optical fiber, clock distribution, and data acquisition system, with benchmarking using arrival times and a computer model to optimize teleportation fidelity and indistinguishability, employing fiber-coupled devices and off-the-shelf optics for multi-node networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quantum teleportation is performed using practical fiber-coupled devices, then ease of manufacture and deployment is improved, but teleportation fidelity deteriorates (stuck below 90%)
Solution Approach 1:
The patent applies parameter changes by optimizing multiple system parameters simultaneously: photon pair generation rates, timing synchronization windows, spectral filtering bandwidths, and detector gating parameters. This allows the system to achieve >90% fidelity using practical fiber-coupled devices by tuning these parameters to compensate for imperfections in off-the-shelf components.
Solution Approach 2:
The patent implements feedback through real-time monitoring of photon arrival times and coincidence detection rates. The system uses active feedback loops to stabilize the timing synchronization between entangled photon pairs and signal photons, dynamically adjusting delay lines and gating windows to maintain optimal interference conditions despite environmental fluctuations in fiber-optic networks.
2Ease of operation
If polarization qubits are used for quantum teleportation, then ease of preparation and measurement is improved, but reliability deteriorates due to polarization rotation in free space and fibers
Solution Approach 1:
The patent replaces the mechanical/optical polarization control system with a temporal encoding system. Instead of using polarization states that require precise optical alignment and are sensitive to rotation, the system encodes quantum information in the arrival time of photons relative to a clock signal. This substitution eliminates sensitivity to polarization rotation while maintaining ease of preparation and measurement through temporal gating.
3Reliability
If time-bin qubits are used for fiber networks, then independence from polarization transformations is improved, but manufacturing complexity increases
Solution Approach 1:
The patent achieves universality by designing a time-bin qubit system that can operate with standard fiber-optic infrastructure and off-the-shelf detectors. The same apparatus can teleport different quantum states (|0⟩, |1⟩, |+⟩, |−⟩) by varying only the temporal gating parameters, eliminating the need for complex state-specific preparation and measurement devices. This multi-functionality reduces manufacturing complexity while maintaining reliability.
4Measurement precision
If quantum teleportation fidelity is increased beyond 90%, then measurement precision is improved, but device complexity increases due to requirements for specialized equipment
Solution Approach 1:
The patent implements self-service through autonomous calibration and optimization routines. The system automatically characterizes its own components (detectors, fibers, beam splitters) and adjusts operating parameters to achieve optimal fidelity without requiring manual intervention or specialized equipment. This self-calibration capability allows >90% fidelity using standard off-the-shelf devices, avoiding the need for complex specialized equipment.
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
Achieves an average fidelity of ≥90% for time-bin qubits over 22 km of optical fiber, compatible with quantum network devices like quantum memories and transducers, using a compact setup with low-dark-count detectors and off-the-shelf optics, facilitating semi-autonomous control and synchronization.
Implementation Method 1
the coupler interacts one of the first photons, carrying a first qubit, and one of the second photons, carrying a second qubit, to form an interference
Implementation Method 2
Individual telecom-band photons (around 1.5 μm wavelength) are ideal carriers of qubits in networks due to their ability to rapidly travel over long distances in deployed optical fibers
Data Source
AI summary
Quantum teleportation is essential for many quantum information technologies, including long-distance quantum networks. Using fiber-coupled devices, including state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optics, we achieve conditional quantum teleportation of time-bin qubits at the telecommunication wavelength of 1536.5 nm. We measure teleportation fidelities of ≥9% that are consistent with an analytical model of our system, which includes realistic imperfections. To demonstrate the compatibility of our setup with deployed quantum networks, we teleport qubits over 22 km of single-mode fiber while transmitting qubits over an additional 22 km of fiber. Our systems, which are compatible with emerging solid-state quantum devices, provide a realistic foundation for a high-fidelity quantum Internet with practical devices.