Towards Ultra-High Vacuum Operation in a TEM for Quantum-Computer-Enhanced Electron Microscopy

Abstract

Quantum electron microscopy is an emerging research field at the intersection of electron microscopy, quantum optics, and nanophotonics. Free electrons can serve as powerful quantum probes, on par with photons in their ability to carry and transfer quantum information, generate entanglement within and with a specimen, and reveal previously inaccessible details on nanoscale quantum phenomena [1]. However, quantum experiments are generally highly sensitive to decoherence arising from interactions with residual gas particles, making ultra-high vacuum (UHV) conditions sometimes essential. UHV environments are also required in transmission electron microscopes (TEMs) for the investigation of contamination-sensitive materials [2, 3]. In our project, we aim to combine a trapped-ion quantum computer with a TEM to realise Quantum-Computer-Enhanced Electron Microscopy (QCEM) (www.qcem.info). In this scheme, coherent interactions between free electrons and a trapped ion require vacuum conditions beyond the standard TEM operation [4]. Although UHV-TEM systems have previously been realised [2,3, 5-7], achieving base pressures in the 10⁻⁹ mbar range or better typically involves significant financial investment, long implementation times, and close collaboration with manufacturers. We present a cost-effective, minimally invasive modification to the vacuum system of a JEOL JEM-2100F to reduce the base pressure at the sample position to below 5 × 10⁻⁹ mbar. Our approach is to integrate two additional 50 L/s NEG-ion pumps mounted on flanges near the sample region, with no structural modifications to the microscope. The NEG pumps are integrated into the microscope workflow through controlled activation and regeneration cycles compatible with standard TEM operation. This work represents a practical step toward enabling the realisation of QCEM, and the concept enables a relatively rapid implementation at a moderate cost, which can, in principle, be adapted to any TEM that provides suitable flange access to the sample chamber.