As the digital revolution has now become mainstream, quantum computing and
quantum communication are rising in the consciousness of the field. The
enhanced measurement technologies enabled by quantum phenomena, and the
possibility of scientific progress using new methods, are of particular
interest to researchers around the world.
Recently two researchers at Tampere University, Assistant Professor Robert
Fickler and Doctoral Researcher Markus Hiekkamäki, demonstrated that
two-photon interference can be controlled in a near-perfect way using the
spatial shape of the photon. Their findings were recently published in the
prestigious journal Physical Review Letters.
"Our report shows how a complex light-shaping method can be used to make two
quanta of light interfere with each other in a novel and easily tuneable
way," explains Markus Hiekkamäki.
Single photons (units of light) can have highly complex shapes that are
known to be beneficial for quantum technologies such as quantum
cryptography, super-sensitive measurements, or quantum-enhanced
computational tasks. To make use of these so-called structured photons, it
is crucial to make them interfere with other photons.
"One crucial task in essentially all quantum technological applications is
improving the ability to manipulate quantum states in a more complex and
reliable way. In photonic quantum technologies, this task involves changing
the properties of a single photon as well as interfering multiple photons
with each other;" says Robert Fickler, who leads the Experimental Quantum
Optics group at the university.
Linear optics bring promising solutions to quantum communications
The demonstrated development is especially interesting from the point of
view of high-dimensional quantum information science, where more than a
single bit of quantum information is used per carrier. These more complex
quantum states not only allow the encoding of more information onto a single
photon but are also known to be more noise-resistant in various settings.
The method presented by the research duo holds promise for building new
types of linear optical networks. This paves the way for novel schemes of
photonic quantum-enhanced computing.
"Our experimental demonstration of bunching two photons into multiple
complex spatial shapes is a crucial next step for applying structured
photons to various quantum metrological and informational tasks," continues
Markus Hiekkamäki.
The researchers now aim at utilizing the method for developing new
quantum-enhanced sensing techniques, while exploring more complex spatial
structures of photons and developing new approaches for computational
systems using quantum states.
"We hope that these results inspire more research into the fundamental
limits of photon shaping. Our findings might also trigger the development of
new quantum technologies, e.g. improved noise-tolerant quantum communication
or innovative quantum computation schemes, that benefit from such
high-dimensional photonic quantum states," adds Robert Fickler.
Reference:
Markus Hiekkamäki et al, High-Dimensional Two-Photon Interference Effects in
Spatial Modes, Physical Review Letters (2021).
DOI: 10.1103/PhysRevLett.126.123601
Tags:
Physics