2021 Recap from Columbia Quantum's Newest Highly Cited Researchers

Six Columbia Quantum Initiative researchers joined Clarivate’s Highly Cited Researcher list this year. Here, we've compiled some highlights from 2021. 

December 23, 2021

Dmitri Basov: Programmable hyperbolic polaritons in van der Waals semiconductors

A team of researchers led by Columbia Researchers has developed a unique platform to program a layered crystal, producing imaging capabilities beyond common limits on demand.

The discovery is an important step toward control of nanolight, which is light that can access the smallest length scales imaginable. The work also provides insights for the field of optical quantum information processing, which aims to solve difficult problems in computing and communications.  Read More...

An optically excited gas of electronic carriers confined to the planes of the layered van-der Waals semiconductor tungsten diselenide is shown. The consequent hyperbolic response permits passage of nanolight. CREDIT Ella Maru Studio

Cory Dean: Electrically tunable correlated and topological states in twisted monolayer–bilayer graphene

Since the discovery of graphene more than 15 years ago, researchers have been in a global race to unlock its unique properties. Not only is graphene—a one-atom-thick sheet of carbon arranged in a hexagonal lattice—the strongest, thinnest material known to man, it is also an excellent conductor of heat and electricity.

Now, a team of researchers at Columbia University and the University of Washington has discovered that a variety of exotic electronic states, including a rare form of magnetism, can arise in a three-layer graphene structure. Read More...

Stacking monolayer and bilayer graphene sheets with a twist leads to new collective electronic states, including a rare form of magnetism. Credit: Columbia University

Alexander Gaeta: Dynamic control of photon lifetime for quantum random number generation

In a passive cavity geometry, there exists a trade-off between resonant enhancement and response time, which is inherently limited by the cavity photon lifetime. The authors present a compelling approach to achieving frequency-selective, dynamic control of the cavity photon lifetime using a coupled-ring geometry. The photon lifetime is tuned by controlling the spectral position of an avoided mode-crossing using thermo-optic tuning with integrated resistive heaters. Read More...

Microscope Image of SiN coupled-ring device. The mode interaction position is thermally tuned via integrated heaters to turn on and off the degenerate parametric oscillator for random number generation.

James Hone: Enhanced tunable second harmonic generation from twistable interfaces and vertical superlattices in boron nitride homostructures

Nonlinear optics, a study of how light interacts with matter, is critical to many photonic applications, from the green laser pointers we’re all familiar with to intense broadband (white) light sources for quantum photonics that enable optical quantum computing, super-resolution imaging, optical sensing and ranging, and more. Through nonlinear optics, researchers are discovering new ways to use light, from getting a closer look at ultrafast processes in physics, biology, and chemistry to enhancing communication and navigation, solar energy harvesting, medical testing, and cybersecurity.

Columbia Engineering researchers report that they developed a new, efficient way to modulate and enhance an important type of nonlinear optical process: optical second harmonic generation—where two input photons are combined in the material to produce one photon with twice the energy—from hexagonal boron nitride through micromechanical rotation and multilayer stacking. Read More...

Two slabs of boron nitride crystals are dynamically twisted with respect to each other. At certain angles, the incoming laser light (orange beam) can be efficiently converted to higher energy light (pink beam), as a result of micromechanical symmetry breaking. Credit: Columbia Engineering

Michal Lipson: Robust, efficient, micrometre-scale phase modulators at visible wavelengths

A visible-spectrum, compact, power-efficient, low-loss phase modulator is a breakthrough in integrated photonics; the device will improve LIDAR for remote sensing, AR/VR goggles, quantum information processing chips, implantable optogenetic probes, and more. Read More...

A visible-spectrum phase modulator (the ring at the center of a radius of 10 microns) is much smaller than a grain of pollen of the morning glory. Credit: Heqing Huang and Cheng-Chia Tsai/Columbia Engineering

Xiaoyang Zhu: Interlayer electronic coupling on demand in a 2D magnetic semiconductor 

Semiconductors can be induced to emit packets of light called excitons; the color of these excitons, however, depends on the underlying material. To change the color, you used to have to change the material.

New work from researchers at Columbia shows that exciton emissions from a two-dimensional semiconductor can be changed by applying a magnetic field. "This is the first example in materials science where you can change the color with a magnet," said Zhu.