A research team of the institute of semiconductor optics and functional interfaces (IHFG) of the University of Stuttgart experimentally verified the generation of polarization-entangled photon pairs in the emission wavelength range of the telecom C-band. The generation of entangled photons, i.e. a non-classical phenomenon which “bounds” the states of two different entities, is a cornerstone for the realization of quantum networks.
Quantum dots are one of the most prominent and promising candidates as non-classical light sources applied in quantum information technology. They have been proven to be able to emit single, indistinguishable and also polarization-entangled photon pairs via the biexciton-exciton cascade.
All these properties have been demonstrated in the NIR regime (i.e. around 900 nm) and here, for the first time, the entangled photon emission was increased up to 1550 nm, key wavelength for fiber-based long-distance classical and quantum communication.
So far the best QD performances have been realized using InAs dots on GaAs platform (naturally emitting at NIR wavelength). This motivated the team of Prof. Dr. Peter Michler to push such a technology up to telecommunication wavelengths.
After long efforts, in close collaboration with the epitaxy team led by Dr. Michael Jetter, it was possible to reach such a milestone, i.e. utilizing In(Ga)As dots to emit telecom-wavelength photons.
The demonstrated entanglement generation in such a system foresees the possibility to extend the unique capabilities reached at NIR up to telecom wavelength. Emission in this regime represents a fundamental skill for fiber-based applications and additionally it is useful for satellite communication, since it marks an atmospheric transmission window.
After the verification of the single-photon nature of the harvested light, moreover an extraordinary low exciton fine-structure splitting (FSS) for most of the investigated quantum dots was measured: indeed, a large FSS inhibits the entanglement generation with high fidelity.
Motivated by this observation, a set of polarization-resolved cross-correlation experiments was performed on an exemplary dot in order to reconstruct the two-photon polarization state that finally reveals the degree of entanglement.
It was found that the detected photons are indeed entangled, which opens the path towards the application of quantum dots in long-distance communication and cryptography schemes. This work represents an important step forward towards the realization of long-distance quantum applications.
Andrea Mayer-Grenu | idw - Informationsdienst Wissenschaft
Basque researchers turn light upside down
23.02.2018 | Elhuyar Fundazioa
Attoseconds break into atomic interior
23.02.2018 | Max-Planck-Institut für Quantenoptik
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy