Closed-cycle cryostat with 12 T magnet and optical inset for confocal measurements

The subject of this application is an optical setup for measuring spatially resolved resonance fluorescence. The instrument is intended to be used to investigate the versatility of quantum dots and single-photon emitters in 2D materials as building blocks in future quantum networks. For the realization of a robust spin-photon interface, both the optical properties of a single-photon source and the electrical addressability of the spin must be investigated and understood. For this purpose, time-resolved, high-resolution optical measurements (gamma-photoluminescence, differential reflectance, and resonance fluorescence) will be combined with electrical transport measurements of quantum dots and single-photon emitters in two-dimensional materials. We will develop scalable quantum dot devices that have excellent control over tunnel coupling and energy levels. We will investigate the level scheme in these quantum dots and measure important limitations for quantum operations, such as the lifetimes and coherence times of spin and valley states. The study will focus on single-photon emission, spin-selective optical transitions, and quantum state preparation. A spin-photon interface will be created by demonstrating optical initialization and read-out of spin or valley states via the optical Raman process for quantum dots in 2D materials. This major research instrument has been designed to realize these sophisticated measurement capabilities. A cryostat with a base temperature of 2 K and magnetic fields of 12 T is needed. A magnetic field of 12 T at 2 K will allow the addressing of different spin states in a quantum dot with high fidelity. Part of the cryostat is an inset for confocal measurements that enables high-resolution optical studies on single-photon emitters in 2D materials via a cooled microscope objective and low-temperature piezo actuators. The major research instrument will be necessary for the continuation of an already ongoing project in the Cluster of Excellence ML4Q and the graduate school TIDE, and it will be used in a planned subproject of a SFB, future DFG individual proposals, and a targeted ERC Starting Grant.

DFG Programme Major Research Instrumentation

Major Instrumentation Geschlossener heliumfreier Kryostat mit 12 T Magnet und Einsatz für konfokale optische Messungen

Instrumentation Group 8550 Spezielle Kryostaten (für tiefste Temperaturen)

Applicant Institution Universität zu Köln

Leader Professorin Dr. Annika Kurzmann