## 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.

**Sample publications**:
arXiv:quant-ph/0512071

## 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.

## 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.

## Atomic, molecular, and optical physics

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