News

• Our new article, "Complementary probes of gravitational radiation states," is now published in Physical Review A

• Sreenath K. Manikandan is joining the Tata Institute of Fundamental Research (TIFR) Hyderabad as a Reader!

I am delighted to share the news that I will be joining the Tata Institute of Fundamental Research (TIFR) Hyderabad, India, as a Reader by November this year! I deeply appreciate TIFRH as a center for interdisciplinary sciences. I look forward to the opportunities this brings to work with excellent colleagues, students, and early-career researchers at the frontiers of quantum science, in a vibrant and supportive academic environment offered by the Tata Institute.

Featured Research in News:

Most recent articles: 

• "Detector Correlations and Null Tests of the Coherent State Hypothesis." Sreenath K. Manikandan, and Frank Wilczek. arXiv preprint arXiv:2508.03367 (2025).

Imagine two people independently counting water droplets in the rain. The droplets will be distributed Poissonian, and the correlation of counts vanishes. We propose statistical null tests in a similar spirit to probe the quantumness of radiation fields using two resonant detectors, with implications for probing the quantum nature of gravitational radiation using two resonant mass detectors. The statistical tests are formulated as tests of the coherent state hypothesis, which are designed to yield the null outcome "zero" if the radiation field is in a coherent state. Violations of the coherent state hypothesis, if observed in experiments, would demonstrate the necessity of bringing in a richer quantum description for the radiation field through the breakdown of optical equivalence. Tests of this nature using independent detector cross-correlations could offer an advantage compared to statistical tests possible using a single detector we previously proposed,  as the vacuum quantum noise of the detectors is naturally excluded in detector cross-correlations.

• "Squeezed Quasinormal Modes from Nonlinear Gravitational Effects." Sreenath K. Manikandan, and Frank Wilczek. arXiv preprint arXiv:2508.03380 (2025).

Given the inherent nonlinearity of general relativity, one might suspect that the quantum-mechanical treatment of gravitational radiation would bring in squeezing. But identifying situations where the degree of squeezing can be calculated systematically is a challenging task. It is an important question, since measurement of such squeezing will be definitive evidence that one must get beyond modeling based on coherent states, which are the hallmark of classical radiation fields. In this work, we address that challenge. Using a perturbative calculation, we show that the dynamics of black hole quasinormal modes, which dominate the late-time gravitational wave signal following black hole merger, lead to quantum-mechanical squeezing. More specifically, we estimate the degree of squeezing generated for the fundamental quasinormal mode of a Schwarzschild singularity, finding, with conservative assumptions about initial conditions, that it is of the order of one percent.