Indistinguishable Photons Advance Quantum Technologies with 94.2% Interference Visibility
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The creation of perfectly matched photon pairs is crucial for advances in quantum technologies, including secure communication and powerful quantum computing, and researchers are continually seeking more reliable and efficient sources. Timon L. Baltisberger from University of Basel, Francesco Salusti from Paderborn University, and Mark R. Hogg from University of Basel, alongside colleagues, now demonstrate a significant step forward by generating highly indistinguishable photons from a unique process involving a cascade of light emissions within a diamond structure.
The team achieves exceptional two-photon interference, reaching 94% for one photon and 82% for the other, by carefully controlling the emission process and minimising noise within the device. This breakthrough establishes a clear relationship between photon coherence and emission timing, paving the way for more stable and predictable quantum light sources and bringing practical quantum technologies closer to realisation.
Indistinguishable Photons From Quantum Dot Microcavities This research details the methods and analysis used to generate indistinguishable photons from a quantum dot system embedded within a microcavity.
The team focused on characterizing single photons and polarization-entangled photon pairs, employing precise optical control and measurement techniques. Scientists measured the second-order correlation function to confirm single photon emission and calculated the Hong-Ou-Mandel visibility to assess photon indistinguishability. A crucial aspect of the work involved rigorous data analysis and correction procedures to ensure accuracy, including a method to analyze how photon purity changes with measurement parameters and identify a reliable noise threshold.
The team also accounted for imperfections in the experimental setup, including classical visibility limitations, finite single-photon emission probabilities, and deviations in beam splitter reflectivity. This detailed account of the experimental methods and data analysis techniques ensures the reliability of the results and provides a foundation for future work in this field. High-Visibility Two-Photon Interference from Semiconductor Dots Scientists have achieved a significant breakthrough in photon coherence using a biexciton cascade in a semiconductor dot, demonstrating high two-photon interference visibility for both photons. The research team measured a visibility of 94 ±2% for one photon and 82 ±6% for the other, representing a substantial improvement in coherence. This achievement stems from enhancing the biexciton transition using a Purcell effect within a low-noise device, effectively manipulating the photons’ lifetimes. The study explored the relationship between photon coherence and the ratio of photon lifetimes, tuning this ratio over two orders of magnitude. Experiments revealed that by carefully controlling the cavity environment, the team could significantly reduce timing jitter, a key factor limiting coherence. The experimental setup utilizes a quantum dot embedded within an open microcavity, achieving a high Q-factor. By tuning the cavity length, scientists precisely controlled the resonance conditions, allowing for manipulation of the photon lifetimes. These results confirm the theoretical model predicting that controlling the lifetime ratio is a powerful strategy for enhancing photon coherence, paving the way for advanced quantum technologies. Predictable Coherence in Semiconductor Photon Pairs Scientists have demonstrated a high degree of coherence in photon pairs generated from a semiconductor nanocrystal, a key step towards practical quantum technologies. The research team achieved high visibility in two-photon interference, reaching 94.2% for one photon and 82.6% for the other, demonstrating a significant improvement in the quality of emitted light. This coherence was attained by carefully enhancing the emission process within the nanocrystal using a technique that amplifies light emission, effectively reducing noise. Importantly, the team found that by adjusting the relative lifetimes of the emitted photons, they could predictably control the coherence, confirming established principles of optics. This control is crucial for applications requiring precisely timed and correlated photons. Future work, they suggest, could focus on further refining the device to minimize noise and improve the efficiency of photon generation, paving the way for more complex quantum circuits and communication systems. 👉 More information 🗞 Indistinguishable photons from a two-photon cascade 🧠 ArXiv: https://arxiv.org/abs/2512.16617 Tags: Quantum Strategist While other quantum journalists focus on technical breakthroughs, Regina is tracking the money flows, policy decisions, and international dynamics that will actually determine whether quantum computing changes the world or becomes an expensive academic curiosity. She's spent enough time in government meetings to know that the most important quantum developments often happen in budget committees and international trade negotiations, not just research labs. Latest Posts by Quantum Strategist: Quantumsavory Achieves Unified Simulation, Enabling Rapid Accuracy-Performance Tradeoffs for Computing and Networking December 19, 2025 Entanglement Limits Quantum Network Performance, Showing Fidelity Can Decrease with More Resources December 19, 2025 Advances in Topological Magic Response Enable Robust Quantum Information Storage December 19, 2025