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Prof. Dr. Philipp Treutlein

Department of Physics
Profiles & Affiliations

Quantum physics of atoms, photons and phonons

The Treutlein group’s research is focused on the quantum physics of atoms, photons and phonons and their interactions. Atoms, light and nanomechanical oscillators are among the best controlled quantum systems. We exploit this control for novel experiments on the foundations of quantum physics and for developing new applications in quantum technology, with a specific focus on quantum metrology and quantum networking.

Our group has developed expertise with three experimental platforms: ultracold atoms in chip-based magnetic and optical traps, miniaturized atomic vapor cells near room temperature, and membrane optomechanical systems. All three systems have in common that they offer a light-matter quantum interface that allows for quantum-limited control, detection and interactions of a massive many-particle system with light. We harness this interface for experiments on the foundations of quantum physics with massive systems of increasing size and complexity, to engineer light-mediated interactions between different massive quantum systems, and to demonstrate new approaches to quantum networking and quantum metrology. Over the years, we have reported a number of experimental breakthroughs, often based on new concepts and ideas that we developed in our group or in close collaboration with our theory collaborators.

Our group is part of the Basel Quantum Center and the Swiss Nanoscience Institute and sustains a number of fruitful collaborations with research groups around the world.

Selected Publications

Mottola, R., Buser, G., & Treutlein, P. (2023). Optical Memory in a Microfabricated Rubidium Vapor Cell. Physical Review Letters, 131(26). https://doi.org/10.1103/physrevlett.131.260801

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Colciaghi, P., Li, Y., Treutlein, P., & Zibold, T. (2023). Einstein-Podolsky-Rosen Experiment with Two Bose-Einstein Condensates. Physical Review X, 13(2). https://doi.org/10.1103/physrevx.13.021031

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Karg, Thomas M., Gouraud, Baptiste, Ngai, Chun Tat, Schmid, Gian-Luca, Hammerer, Klemens, & Treutlein, Philipp. (2020). Light-mediated strong coupling between a mechanical oscillator and atomic spins 1 meter apart. Science, 369(6500), 174–179. https://doi.org/10.1126/science.abb0328

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Fadel, Matteo, Zibold, Tilman, Décamps, Boris, & Treutlein, Philipp. (2018). Spatial entanglement patterns and Einstein-Podolsky-Rosen steering in Bose-Einstein condensates. Science, 360(6387), 409–413. https://doi.org/10.1126/science.aao1850

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Schmied, Roman, Bancal, Jean-Daniel, Allard, Baptiste, Fadel, Matteo, Scarani, Valerio, Treutlein, Philipp, & Sangouard, Nicolas. (2016). Bell correlations in a Bose-Einstein condensate. Science, 352(6284), 441–444. https://doi.org/10.1126/science.aad8665

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Selected Projects & Collaborations

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Scalable High Bandwidth Quantum Network (sQnet)

Research Project  | 2 Project Members

Realizing a scalable quantum network is one of the grand challenges of quantum technology, with numerous potential applications in secure communication, quantum sensor networks, and distributed quantum computation. Single-photon sources and compatible quantum memories are key ingredients of quantum networks and the requirements on their performance are very stringent. In this project we will establish a scalable quantum networking platform that combines several high-performance elements: semiconductor quantum dot single-photon sources and compatible atomic vapor cell quantum memories implemented in scalable MEMS technology, operating with GHz bandwidth at convenient near-infrared wavelengths. Connectivity over long distance and to other platforms is enabled by efficient conversion of single photons to telecom wavelength using on-chip nonlinear optics. Combining these building blocks, we will demonstrate quantum networking tasks such as remote entanglement generation between quantum memories over a telecom fiber link. By demonstrating the basic functionality of a scalable quantum networking platform that operates at high efficiency and bandwidth, the project will lay the ground for the implementation of more advanced quantum networking protocols and scaling to multiple nodes.

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Non-classical correlations in ultracold atomic ensembles

Research Project  | 1 Project Members

Non-classical correlations between quantum systems lead to the most striking departure of quantum from classical physics. Despite decades of research, such correlations still present many conceptual and experimental challenges, while at the same time their key role in quantum technologies is recognised. This is particularly true for systems of many particles, where different classes of non-classical states exist with different usefulness for technological tasks. There are open questions on how to generate, control, detect, and exploit non-classical correlations, in particular in large ensembles where access to individual particles is limited. To elucidate these questions has become a subject of intense research on different experimental platforms. Ultracold atomic ensembles are quantum many-particle systems par excellence: (1) atoms are very well isolated from the environment and feature long coherence times, (2) ensembles with adjustable atom number from a few hundreds to millions can be reliably generated, (3) a powerful toolbox for control and measurement of their quantum state is available, and (4) atom-atom interactions can be tuned and engineered to generate correlations in a controlled way. These unique features make ultracold atomic ensembles an ideal system for the experimental study of non-classical correlations in many-particle systems, which is the overarching goal of this project. We will use two complementary approaches to pursue this goal: In the first approach, we will investigate atomic two-component Bose-Einstein condensates on an atom chip. Non-classical correlations between the atomic spins are generated by controlled collisions in a state-dependent potential. A specific focus of the experiments will be the distribution of non-classical correlations from one to several spatially separated and individually addressable condensates, with the goal to demonstrate entanglement and Einstein-Podolsky-Rosen steering and to investigate schemes for interferometry with spatially split condensates near the atom chip surface. In the second approach we will explore a new scheme for generating non-classical correlations in large atomic spin ensembles based on light-mediated Hamiltonian interactions. Using a new experimental setup with ultracold atoms in an optical dipole trap, we will generate collective spin-spin interactions by multi-pass atom-light interactions with free-space laser beams. This scheme is promising for quantum manipulation of large atomic ensembles in a simple geometry, potentially interesting for precision metrology. This project is expected to lead to novel insights into generation and control of non-classical correlations in ultracold atomic ensembles, their distribution into spatially separated, individually controllable systems, and their use in quantum technologies, in particular sensing, metrology and imaging.

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MACQSIMAL - Miniature Atomic vapor Cells based Quantum devices for SensIng and Metrology AppLications

Research Project  | 1 Project Members

Sensors provide the interface between the real world and the digital world. Quantum technologies are poised to revolutionize this interface, and with it sensor-driven industries such as navigation and medical imaging. MACQSIMAL combines the expertise of world-leading research groups, RTOs and companies, covering the whole knowledge chain from basic science to industrial deployment, and aims at breakthroughs that will firmly establish European leadership in the quantum sensor industry. MACQSIMAL will develop quantum-enabled sensors with outstanding sensitivity for five key physical observables: magnetic fields, time, rotation, electro-magnetic radiation and gas concentration. These sensors are chosen for their high impact and their potential to quickly advance to a product: Within MACQSIMAL all these sensors will reach TRLs between 3 and 6 and will outperform other solutions in the respective markets. The common core technology in these diverse sensors is atomic vapor cells realized as integrated microelectromechanical systems (MEMS). Atomic vapor cells make coherent quantum processes available to applications: advanced cell-based sensors optimally exploit single-particle coherence, with the potential to harness also multi-particle quantum coherence for still greater sensitivity. Fabricating such atomic vapor cells as MEMS allows for high-volume, high-reliability and low-cost deployment of miniaturized, integrated sensors, critical to wide-spread adoption. MACQSIMAL will combine state-of-the-art sensor physics with the MEMS atomic vapor cell platform, for highly advanced prototypes and demonstrators. Concurrently, advanced squeezing, entanglement and cavity-QED methods will be applied for the first time in miniaturized sensors, bringing quantum enhancement closer than ever to industrial application. This advanced, multi-target, quantum-enabled sensor platform will mark the start of a dynamic and multi-sector quantum sensor industry in Europe.

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Modular mechanical-atomic quantum systems

Research Project  | 1 Project Members

Atomic ensembles are routinely prepared and manipulated in the quantum regime using the powerful techniques of laser cooling and trapping. To achieve similar control over the vibrations of nanofabricated mechanical oscillators is a goal that is vigorously pursued, which recently led to the first observations of ground-state cooling and quantum behavior in such systems. In this project, we will explore the new conceptual and experimental possibilities offered by hybrid systems in which the vibrations of a mechanical oscillator are coupled to an ensemble of ultracold atoms. An optomechanics setup and an ultracold atom experiment will be connected by laser light to generate long- distance Hamiltonian interactions between the two systems. This modular approach avoids the technical complications of combining a cryogenic optomechanics experiment and a cold atom experiment into a highly integrated setup. At the same time, it allows to investigate intriguing conceptual questions associated with the remote control of quantum systems. The coupled mechanical-atomic system will be used for a range of experiments on quantum control and quantum metrology of mechanical vibrations. We will implement new schemes for ground-state cooling of mechanical vibrations that overcome some of the limitations of existing techniques, explore coherent mechanical-atomic interactions and Einstein-Podolsky-Rosen entanglement, and use such entanglement for measurements of mechanical vibrations beyond the standard quantum limit. The extensive experience of the PI in atomic quantum metrology and hybrid optomechanics will be a valuable asset in this endeavor. Besides the interesting perspective of observing quantum phenomena in engineered mechanical devices that are visible to the bare eye, the project will open up new avenues for quantum measurement of mechanical vibrations with potential impact on the development of mechanical quantum sensors and transducers for accelerations, forces and fields. Atomic ensembles are routinely prepared and manipulated in the quantum regime using the powerful techniques of laser cooling and trapping. To achieve similar control over the vibrations of nanofabricated mechanical oscillators is a goal that is vigorously pursued, which recently led to the first observations of ground-state cooling and quantum behavior in such systems. In this project, we will explore the new conceptual and experimental possibilities offered by hybrid systems in which the vibrations of a mechanical oscillator are coupled to an ensemble of ultracold atoms. An optomechanics setup and an ultracold atom experiment will be connected by laser light to generate long-distance Hamiltonian interactions between the two systems. This modular approach avoids the technical complications of combining a cryogenic optomechanics experiment and a cold atom experiment into a highly integrated setup. At the same time, it allows to investigate intriguing conceptual questions associated with the remote control of quantum systems. The coupled mechanical-atomic system will be used for a range of experiments on quantum control and quantum metrology of mechanical vibrations. We will implement new schemes for ground-state cooling of mechanical vibrations that overcome some of the limitations of existing techniques, explore coherent mechanical-atomic interactions and Einstein-Podolsky-Rosen entanglement, and use such entanglement for measurements of mechanical vibrations beyond the standard quantum limit. The extensive experience of the PI in atomic quantum metrology and hybrid optomechanics will be a valuable asset in this endeavor. Besides the interesting perspective of observing quantum phenomena in engineered mechanical devices that are visible to the bare eye, the project will open up new avenues for quantum measurement of mechanical vibrations with potential impact on the development of mechanical quantum sensors and transducers for accelerations, forces and fields.