Scientists have discovered a light-induced
switching mechanism in a Dirac semimetal.
The mechanism establishes a new way to control
the topological material, driven by back-and-forth
motion of atoms and electrons, which will
enable topological transistor and quantum
computation using light waves.
Just like today's transistors and photodiodes
replaced vacuum tubes over half a century
ago, scientists are searching for a similar
leap forward in design principles and novel
materials in order to achieve quantum computing
capabilities.
Current computation capacity faces tremendous
challenges in terms of complexity, power consumption,
and speed; to exceed the physical limits reached
as electronics and chips become hotter and
faster, bigger advances are needed.
Particularly at small scales, such issues
have become major obstacles to improving performance.
Light wave topological engineering seeks to
overcome all of these challenges by driving
quantum periodic motion to guide electrons
and atoms via new degrees of freedom, i.e.,
topology, and induce transitions without heating
at unprecedented terahertz frequencies, defined
as one trillion cycles per second, clock rates.
This new coherent control principle is in
stark contrast to any equilibrium tuning methods
used so far, such as electric, magnetic and
strain fields, which have much slower speeds
and higher energy losses.
Wide-scale adoption of new computational principles,
such as quantum computing, requires building
devices in which fragile quantum states are
protected from their noisy environments.
One approach is through the development of
topological quantum computation, in which
qubits are based on "symmetry-protected" quasiparticles
that are immune to noise.
However, scientists who study these topological
materials face a challenge--how to establish
and maintain control of these unique quantum
behaviors in a way that makes applications
like quantum computing possible.
In this experiment, the researchers demonstrated
that control by using light to steer quantum
states in a Dirac semimetal, an exotic material
that exhibits extreme sensitivity due to its
proximity to a broad range of topological
phases.
They achieved this by applying a new light-quantum-control
principle known as mode-selective Raman phonon
coherent oscillations--driving periodic motions
of atoms about the equilibrium position using
short light pulses.
The research work opens a new arena of light
wave topological electronics and phase transitions
controlled by quantum coherence.
This will be useful in the development of
future quantum computing strategies and electronics
with high speed and low energy consumption.
