Research

One of the long-standing questions in physics is how well we can manipulate and control the microscopic world of so-called quantum systems. Over the past few decades, experimental efforts have been made on platforms such as superconductors, photons, trapped ions, and neutral atoms, which have become the basis for quantum technologies currently attracting much attention.

In the neutral atom platform, the kinetic energy of atoms is reduced by laser cooling at room temperature, and the quantum state is controlled by capturing only single atoms using an optical tweezer. Entanglements are implemented by exciting atoms to the Rydberg states, where the size of atoms increases to ~1 um and induces strong atom-atom interactions. Combined with hologram techniques to arrange multiple optical tweezers, the neutral atom platform has shown nice qubit scalability and controllability.

Currently, we are building our experimental setup based on the 87Rubidium atom. We are interested in the following research using this platform.

1. Quantum simulation

Quantum simulation is to understand the properties of a real system of interest using a device that actively uses quantum effects. The system is often modeled as an interacting spin system, and we could get intuitions of the system by observing the time dynamics or quantum phase transitions, etc. We are interested in how versatile Hamiltonians can be implemented using the interactions of Rydberg atoms.

• Relevant work

M. Kim, Y. Song, J. Kim, and J. Ahn, PRX Quantum 1, 020323 (2020).

2. Adiabatic quantum computation

Adiabatic quantum computation applies the time evolution of quantum systems, from an initial state easy to prepare, to a final state according to the adiabatic theorem. A relevant application is combinatorial optimization problems(NP-problems), finding optimal solutions for a given network(or a graph) consisting of several nodes and their connections. We are interested in how the Rydberg atom systems can reduce the computational complexity of combinatorial optimization problems, especially the maximum-independent-set problems with various graphs.

• Relevant work

M. Kim, K. Kim, J. Hwang, E.-G. Moon, and J. Ahn, Nature Physics 18, 755-759 (2022).

A. Byun*, M. Kim*, and J. Ahn, PRX Quantum 3, 030305 (2022).