# Atoms Trapped with Light Behave Like a Dissipative Quantum System

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PT-symmetric non-Hermitian quantum many-body system using ultracold atoms in an optical lattice with controlled dissipation

Prog. Theor. Exp. Phys. **2020**, 12A110 (2020).

A team of researchers from Japan experimentally realize, for the first time, a dissipative, parity-time symmetric, many-body quantum system from ultracold atoms trapped in an optical lattice.

Elementary quantum physics usually tackles quantum systems that are energy-conserving and described well by a Hermitian Hamiltonian. In reality, however, many quantum systems are dissipative in nature and can only be described effectively using a non-Hermitian Hamiltonian. Consequently, non-Hermitian quantum physics has garnered considerable attention from researchers across diverse subfields of physics.

In condensed matter physics, for instance, many-body systems are a widely researched topic. The electrons in these systems interact strongly with one another, giving rise to quantum states that cannot be described by knowing the equation of motion of a single electron. Recent theoretical studies have now revealed that many-body systems can be dissipative with parity-time (or PT)-symmetry and show unique exotic phases with no counterpart in conservative systems.

Against this backdrop, a team of physicists from Japan have recently experimentally realized a PT-symmetric, non-Hermitian, many-body system from ultracold Ytterbium atoms trapped in an optical lattice formed by interfering counter-propagating laser beams. In their study, the team experimentally investigated the ideal conditions for one-and two-body dissipation and developed methods to measure and control relative phases between on- and off-resonant lattices for PT symmetry. Additionally, they constructed a new theoretical framework to predict the appearance of interesting loss dynamics.

The experimental system developed by the team could serve as a future platform for investigating novel and uniquely non-Hermitian quantum phenomena as well as extend the non-Hermitian perspective to other quantum systems, potentially revolutionizing our understanding of many-body systems as a whole.

PT-symmetric non-Hermitian quantum many-body system using ultracold atoms in an optical lattice with controlled dissipation

Prog. Theor. Exp. Phys. **2020**, 12A110 (2020).