Photonic Quantum Control

Dr. Jonas Junker

Email: jonas.junker@uni-jena.de
Phone: +49 3641 9-47994

Carl-Zeiss-Stiftung Logo

Picture: Carl-Zeiss-Stiftung.

Dr. Jonas Junker is a Junior Group Leader at the Institute of Applied Physics and the Abbe Center of Photonics at Friedrich Schiller University Jena. His research focuses on quantum optics and photonic quantum technologies, with particular emphasis on the generation and manipulation of non-classical states of light. The group is supported by the Carl-Zeiss-StiftungExternal link within its Carl-Zeiss-Stiftung Center for Quantum Photonics (CZS Center QPhoton)External link.

Dr. Junker received his PhD from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Hannover, where he developed novel techniques for quantum metrology based on squeezed states of light and back-action evasion. Following his doctoral studies, he conducted postdoctoral research at the Australian National University and the Technical University of Denmark, working on advanced squeezed-light sources and optical quantum information processing. Since 2026, he is establishing the Photonic Quantum Control group in Jena.

Research Overview

The Photonic Quantum Control group explores new methods to manipulate quantum states of light at high bandwidths and with minimal classical control overhead. Our goal is to develop optical platforms that enable quantum information processing and sensing tasks to be performed directly in the optical domain, thereby avoiding electronic bottlenecks.

A central research direction is the use of nonlinear optical processes, such as optical parametric amplification and squeezing, to enable real-time optical control, feed-forward operations, and adaptive quantum measurements. These techniques have applications in photonic quantum computing, quantum sensing, and precision metrology.

The group works at the interface of fundamental quantum optics and emerging quantum technologies, with the long-term aim of developing scalable and high-performance photonic platforms for quantum information processing and sensing.

Research Areas

Current research topics include:

Generation of squeezed and non-classical states of light
All-optical quantum control and feed-forward techniques
Continuous-variable photonic quantum information processing
High-bandwidth quantum measurement and sensing
Optical parametric amplification and nonlinear photonic systems

Teaching Fields

Control Techniques in Quantum Optical Experiments

Research Methods

The group develops and operates advanced experimental platforms for photonic quantum optics, including:

Optical parametric oscillators and amplifiers
Continuous-variable homodyne detection systems
High-bandwidth photonic control and modulation
Precision optical cavities and nonlinear crystals
Advanced laser systems for quantum optics experiments

Recent Research Results

Recent research results include the development of nonlinear optical systems for generating and controlling non-classical states of light for quantum metrology and precision measurements. In particular, recent work demonstrated squeezing generated in a nonlinear coupled-cavity system, revealing quantum noise reduction at the normal-mode splitting frequency of two interacting resonators [1].

Experimental setup of the coupled-cavity squeezing experiment. A nonlinear squeezing cavity containing a χ² crystal is coupled to a test cavity. The generated squeezed field is characterised using balanced homodyne detection
Image: Dr. Jonas Junker

Measured quantum noise spectrum of the squeezed field generated in the coupled-cavity system. The experiment demonstrates quantum noise reduction at the normal-mode splitting frequency around 7.5 MHz
Image: Dr. Jonas Junker

Further contributions include the generation and full quantum-tomographic characterisation of frequency-dependent squeezed states produced by a detuned optical parametric oscillator, enabling tailored quantum-noise spectra for interferometric sensing [2]. Complementary work introduced efficient reconstruction techniques for bipartite Gaussian quantum states using a single polarization-sensitive homodyne detector, significantly simplifying experimental continuous-variable quantum-optics setups [3].

Additional studies investigated phase-sensitive optical parametric amplification of weak optical signals in nonlinear optical systems [4] and demonstrated broadband detection of multimode squeezing combs using high-efficiency photodetection systems for characterising non-classical optical fields over large bandwidths [5].

References

[1] J. Junker et al., Phys. Rev. Lett. 134, 243603 (2025).
[2] J. Junker et al., Phys. Rev. Lett. 129, 033602 (2022).
[3] J. Junker et al., Optics Express 30, 33860 (2022).
[4] K. M. Kwan et al., Phys. Rev. Lett. (accepted, 2026).
[5] D. Wilken et al., Phys. Rev. Appl. 21, L031002 (2024).