Quantum sensing and quantum imaging

Quantum states of light, such as squeezed states or entangled states, can be used to make measurements (metrology), produce images, and sense objects with a precision that far exceeds what is possible classically, and also exceeds what was once thought to be possible quantum mechanically. The primary idea is to exploit quantum effects to beat the shot-noise limit in metrology and the Rayleigh diffraction limit in imaging and sensing.
Sample publications: arXiv:0904.0163, arXiv:quant-ph/9912052,,,

Quantum information theory

What are the ultimate limits that nature imposes on the rate at which we can communicate reliably? How can we use quantum processors to achieve these limits? The broad field of quantum information theory addresses these questions and extends Shannon's classical information theory. Surprises such as quantum teleportation and super-dense coding have extended our understanding of the interplay between classical bits, quantum bits, and entanglement, leading to a variety of quantum channel capacities for information transmission.
Sample publications: arXiv:1206.4886, arXiv:1102.2624

Optical quantum computing

Linear optics with photon counting is a prominent candidate for practical quantum computing. The protocol by Knill, Laflamme, and Milburn [Nature 409, 46 (2001)] explicitly demonstrates that efficient scalable quantum computing with single photons, linear optical elements, and projective measurements is possible. Subsequently, several improvements on this protocol have started to bridge the gap between theoretical scalability and practical implementation.
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Quantum error correction

Quantum processors are inevitably subjected to the deleterious effects of noise. The only way that we will ever have reliable quantum computers or quantum communication devices is if we are able to stabilize these systems against noise, using quantum software routines known as quantum error-correcting codes. Remarkably, such codes can be shown to work in principle and experimental efforts have demonstrated their benefits as well. However, much work remains in the areas of fault-tolerant quantum computation and quantum error correction for communication.
Sample publications: arXiv:1212.2537, arXiv:1010.1256

Foundations of quantum mechanics

What is the simplest formulation of the postulates of quantum mechanics? How does the behavior of quantum mechanical systems change in the presence of exotic spacetime geometries that allow for closed timelike curves? Establishing and simplifying the foundations of quantum mechanics has been one of the oldest programs in physics since the original establishment of the theory, and yet the tools and perspective of quantum information have shed a new light on this subject.
Sample publications: arXiv:1306.1795, arXiv:0811.1209

Quantum computational complexity theory

What are the ultimate practical limits that nature imposes on computation? How do different computational problems relate to each other and how does quantum mechanics change our understanding of computation? The field of quantum computational complexity theory addresses these questions and lies at the intersection of physics and computation. For example, quantum complexity theory helps in characterizing the difficulty of computing the ground state energy of physical Hamiltonians or how hard it is to decide if a quantum state is entangled.
Sample publications: arXiv:1211.6120

Photonic band gap and meta materials

Theory and simulation of photonic materials, nanoscale photonic devices, plasmonics, computational electromagnetics. Recent work has focused on photonic crystals for thermal emissivity control and nanoscale plasmonic devices.

Sample publications: Improving solar cell efficiency using photonic band-gap materials

Quantum optics

Recent work has focused on the the production and detection of nonclassical squeezed or entangled light sources for applications to quantum metrology and imaging.

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Atomic, molecular, and optical physics

Investigations into electromagnetically induced transparency, slow- and fast-light, and nonlinear optics.

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Relativistic quantum mechanics and field theory

Investigations into different aspects of quantum systems in special and general relativistic spacetimes.  Recent work has focused on both, foundational aspects and applications, mainly in the context of black holes and cosmology, and quantum anomalies of the electromagnetic field. 

Sample publications: arXiv:1503.03407 , arXiv:1412.3524, arXiv:1607.08879, arXiv:1810.08085