Welcome!

I am a physicist specialising in the theory of quantum fluids in cold atoms and superconductors. Together with my collaborators, we are interested in discovering and understanding novel phenomena in far-from-equilibrium scenarios. We employ both analytical and numerical tools to model the dynamics of various many-body systems. 

Further details about our research can be found in the research and publications sections.

Research highlights are shown in the gallery below -- click the pictures for more information.

Observation of a continuous time crystal Science(Phys.org, NewScientist)
Condensate formation in a dark state of a driven atom-cavity systemPhysical Review Letters (Cover, News)
Observation of a Dissipative Time Crystal Physical Review Letters(Viewpoint, News)
Dynamical control of order in a cavity-BEC system Physical Review Letters(News)
Realization of a Periodically Driven Open Three-Level Dicke ModelPhysical Review Letters
Higgs time crystal in a high-Tc superconductor Physical Review Research(News

Recent Activities

17 April 2024

Origin of time crystals in fully-connected spin-cavity systems

A novel phase of matter called discrete time crystals has been predicted and later on experimentally observed in a dissipative atom-cavity system. Time crystals are known for exhibiting emergent patterns in time and those observed in the atom-cavity platform exhibit what is known as a period-doubling behaviour, which means it takes two cycles of the external periodic drive for the system to return to its original configuration. For this type of time crystal and, in general, for spin systems with all-to-all interactions, we proposed a theory based on parametric resonance to understand the origin of this curious phase of matter. It turns out that fundamentally, the slow response of the time crystal shares the same phenomenology with a child moving up and down on a swing. However, in the case of a time crystal, we found that interaction with the environment and an additional symmetry breaking are both required for the symmetry-breaking period-doubling response to be stable.


arXiv:2402.03729v2

Physical Review A


28 February 2024

Counterflow currents in bilayer superconductors

Superconductivity and its defining feature of dissipationless or resistanceless flow of charged currents are expected to vanish when a material's temperature exceeds the critical temperature for superconductivity. In our work, we predict that some version of the dissipationless current survives even above the critical temperature. However, the currents flow in opposite directions in each superconducting layer of a bilayer superconductor. Our work is consistent with one of the proposed scenarios in the less understood "pseudogap phase" in high-temperature superconductors.


arXiv:2309.04531

Physical Review Letters


6 July 2023

Time crystals could be made stronger by their environment

Time crystals are a phase of matter known for their formation of patterns in time. They can be created by periodic driving or “shaking”, and their unique signature is a response slower than the rate of the shaking. It has been observed that time crystals can be created using cold atoms interacting via light that could escape or “dissipate” into the environment in a controlled way. However, it remains a mystery what the precise role of the dissipating light plays in the formation of this type of time crystal. In our work published in Physical Review B, we shed light on this by using extensive numerical simulations to show how dissipation could make the time crystals more robust against noise and imperfections. It does so by increasing the number of combinations of parameters that could form a time crystal. We find that there is a “Goldilocks zone” for the dissipation strength – too weak or too strong could make a time crystal less robust. We also identify the fundamental mechanism for the creation of such a time crystal to be a “parametric resonance” – the same process that leads to larger swinging of a pendulum that is periodically shifted up and down.


arXiv:2303.13334

Physical Review B


22 April 2023

Condensate formation in a dark state of a driven atom-cavity system

Our work was recently published in Physical Review Letters and was chosen to be on the cover of that issue. In this work, we have predicted and experimentally observed that a Bose-Einstein condensate may form in a dark state of a periodically shaken atom-cavity system. We have shown that the photon-mediated interactions can lead to the occupation of a dark state, which demonstrates a mechanism for efficiently preparing complex many-body states in open quantum systems.


arXiv:2209.03342

Physical Review Letters


27 June 2022

Observation of a continuous time crystal

In our work published in Science chosen for "First Release", we demonstrate the first observation of a continuous time crystal in a lab. This time crystal is very close to the original time crystal proposed by Nobel laureate, Frank Wilczek, in his seminal work in 2012. A continuous time crystal is similar to a standard crystal, like ice, where we know that there is a periodic pattern in space but we can not pinpoint the exact location of the molecules. In a continuous time crystal, the time when the system starts to oscillate is random. 

We specifically use a Bose-Einstein condensate inside an optical cavity to demonstrate that limit cycles, marked by oscillating photon occupation in the cavity,  may emerge in the system under the right conditions. We showed that these limit cycles exhibit the robustness and spontaneous symmetry breaking expected of a continuous time crystal. 


arXiv:2202.06980

Science


News articles and interviews:

"Researchers observe continuous time crystal" (Phys.org)

"A new kind of time crystal has been created and lasts 10 milliseconds" (NewScientist)