adapted from: https://uwaterloo.ca/institute-for-quantum-computing/news/iqc-researcher-wins-dean-science-award
Sainath’s research is based on trapped ultracold ions for quantum computing and quantum simulation in Prof. Islam’s Laboratory for Quantum Information with Trapped Ions. Their ion trap is designed to hold a string of ions, where each ion is a qubit in a quantum processor. The aim of his research is to perform quantum simulations that will enable the study of physics too complex for classical computers.
Quantum simulations with trapped ions are broadly classified into two categories, analog and digital simulations. Analog quantum simulations exactly replicate the system Hamiltonian, the rules for how a quantum system will evolve over time. This method is restricted to a few classes of Hamiltonians. By contrast, in a digital quantum simulation, the evolution of a Hamiltonian is broken up into multiple single- and two-qubit gates, and can be applied to a much broader range of problems. This method has challenges, such as the scaling of errors with system size.
Sainath developed a hybrid analog-digital protocol, which is more versatile than the analog method and less error-prone than the digital method. The protocol also takes fewer experimental resources than other quantum simulations, making it more amenable to experimental implementation. Furthermore, most protocols would require the ability to address each ion in the string individually, whereas this new protocol doesn’t. The work formed the basis of a peer-reviewed publication in Nature Partner Journals Quantum Information (5:32 (2019)), as a collaborative work between Sainath, IQC postdoc Fereshteh Rajabi, and scientists from UW, UC Berkeley, and Army Research Laboratory (Maryland).
This protocol allows switching between lattice geometries during the evolution of the system, which is not physically possible with most other physical implementation. This allows new simulations of the rich physics at the boundary of transitions between phases of matter. No one knows what happens during phase transitions between different geometries, so it will be really exciting to explore them with this protocol.
Sainath chose to stay at the Department of Physics & Astronomy and Institute for Quantum Computing to pursue the PhD. He plans, now that the experiment is trapping and laser-cooling ions, to implement his new quantum simulation methods in the laboratory. He will be able to study various problems in physics such as Hamiltonian quenches, dynamical phase transitions and quantum transport in higher dimensions using 1D chains of ions.
“As a physicist, it is just fascinating to study these fundamental problems.”, said Sainath.
