Quantum simulation with engineered dissipation

In recent years, there has been significant progress in the fields of quantum physics and quantum control in integrating novel interactions with ultracold atoms to realize exotic phases of strongly correlated matter and perform quantum operations. However, there is still a frontier that largely remains unexplored, associated with achieving strong interactions of long-range character. Although it is well-known that, in principle, photon-mediated interactions provide an enabling route, in practice, large and uncontrolled dissipation in the form of atomic spontaneous emission greatly limits what is actually achievable. For this collaborative project QuSiED, the targeted breakthrough is to overcome this barrier by constructing a new platform consisting of a many-atom Ytterbium optical tweezer array integrated with a cavity QED setup. While spontaneous emission typically limits the interaction fidelities of light- matter coupled systems, our setup will instead harness spontaneous emission as a correlated form of dissipation, which can be suppressed and even utilized for dissipation engineering given the ability to controllably position atoms at sub-wavelength distances. In a tight collaboration between theory and experiment, a new apparatus will be made operational combining ultracold Yb atoms, optical tweezers for subwavelength-spacing of the atoms, and a high- finesse cavity. The anticipated increases in interaction fidelities (to the 99 percent level), and versatility to design long-range interactions and dissipation, will make such a platform a leading candidate for future applications in quantum simulation and metrology via the ability to produce, investigate, and utilize novel exotic dissipative phases of matter. Such a gain over current capabilities will come from novel experimental advances, a new conceptual paradigm of light-matter interactions, and new theoretical approaches that will be combined together by the diverse QuSiED partners. QuSiED will investigate fundamental problems like the formation of dissipative phases without thermodynamic counterpart, as well as aspects of many-body quantum information science, ranging from entanglement transport in the presence of engineered dissipation to prospects for metrology enhanced by correlated emission. The realization of the unique tweezer-cavity platform will establish a significant advantage for the EU`s race for quantum supremacy with the diverse QuSiED consortium creating interdisciplinary knowledge ranging from fundamental to applied aspects of long-range photon-mediated interactions and engineered dissipation.

The project Quantum Simulation with Engineered Dissipation (QuSiED) explored new ways of controlling and understanding quantum systems made of light and atoms. It was part of the QuantERA European research network, involving teams from Austria, Slovenia, Hungary, Spain, and Germany. The Innsbruck group focused on building an advanced experimental setup combining ultracold Ytterbium atoms with a high-finesse optical cavity. This platform allows atoms to interact with one another through shared photons, enabling the study of collective quantum behavior and the development of light-matter interfaces for future quantum communication technologies. During the project, the team made major technical progress. They constructed the complete ultra-high-vacuum apparatus, realized laser cooling of Ytterbium atoms to about 20 microkelvin, and created a Bose-Einstein condensates (BECs) of Ytterbium in this new system. The researchers also designed a vibration-isolated cavity platform for precision measurements and developed a high-resolution optical tweezer system for single-atom control. These achievements establish the foundation for future experiments on photon-mediated quantum interactions and engineered dissipation. The project was carried out by a small and dedicated team including a postdoctoral researcher, Dr. Dizhou Xie funded through QuantERA and a PhD student, Reza Masala Nejad, who led much of the experimental work. Although no scientific publications have yet resulted, QuSiED has successfully built the envisioned infrastructure and expertise to pursue next-generation quantum simulation and communication research in Austria and across Europe.