### Quantum Simulation With Trapped Ions

Many outstanding problems of modern physics involve understanding the origin and properties of strongly interacting quantum systems. Such correlated quantum systems – such as the high-Tc superconductors and quark-gluon plasma in a particle collider – are present in various energy scales. In an interacting quantum system, entanglement or non-classical correlations between parts often makes theoretical or numerical analysis intractable. An experimental way to solve this problem is to simulate quantum models using well-controlled quantum systems in the laboratory. In these experimental ‘quantum simulators’, it is possible to add complexities and increase the system size in a controlled way. The long quantum coherence in these systems allow their temporal evolution following the quantum laws of nature. The task of the experimentalist is then to initialize the system in a known state, engineer the desired quantum Hamiltonian, let the system evolve in isolation from its environment, and finally measure the outcome. The knowledge gained from studying non-trivial quantum models can potentially lead to the understanding of exotic quantum phases of matter, and give fundamental insights towards realizing quantum computers.

At the QITI laboratory, we are using laser-cooled trapped Ytterbium ions (Yb+) for quantum simulation of spin models. The long range Coulomb interaction between the ions would be exploited to engineer versatile spin Hamiltonians. The spin interactions can be tuned, in principle arbitrarily, and the individual spins can be detected with near perfection. Interacting Hamiltonians and open quantum systems are often hard to simulate on classical computers, and may become intractable beyond 30-40 spins. The QITI laboratory aims to work in the regime where classical computation is difficult or intractable.

See the publication below:

### QuantumION - an open-access quantum computer for the research community

Together with Prof. Crystal Senko’s group, we are building an open-access, remotely operable trapped ion quantum computer (QuantumION). The hardware is based on 133Ba+ qubits in a Sandia HOA trap, with individual laser addressing to be able to perform arbitrary single and two-qubit quantum gates. QuantumION is supported by Transformative Quantum Technologies (TQT).

### Machine learning in Quantum Information processing

We research on classical and quantum algorithms to make quantum simulators more efficient and versatile. For example, we collaborate with the Perimeter Institute Quantum Intelligence Laboratory to incorporate machine learning methods in programming a quantum simulator. See below for an example.

# 1. [2020] Machine learning design of a trapped-ion quantum spin simulator

Quantum Sci. Technol. 5, 024001 (2020) arXiv:1910.02496

### Job Opportunities in the group

**Undergraduate research assistants** - We hire undergraduate co-op students through the waterlooworks website. We work with undergraduate students accepted through IQC’s USEQIP
program, PHYS 437 students, and volunteering undergrads. Contact the PI with your CV and a short description of what you are interested in. We especially welcome students who enjoy hands-on experimental research.

**Graduate students** - Motivated students are encouraged to apply for graduate school (MSc and PhD) through the Dept. of Physics and Astronomy, University of Waterloo. Students with experience working in AMO laboratories will be give priority. While Waterloo typically admits grad students for the Fall (starting Sep) term, we can also admit strong candidates either in Winter (starting Jan) or Spring (starting May) terms. E-mail the PI if you are interested with CV and a to-the-point description of your research background and interests.

**Postdoctoral Fellow**: Please contact the PI at krislam@uwaterloo.ca if you are interested in postdoctoral positions with one of the two research efforts - the Quantum simulation lab and the QuantumION project.