researchers from basel, bochum and copenhagen ‘ve gained new insites inna'da energy states of quantum dots. they are semiconductor nanostructures and promising building blocks for quantum communication. with their experiments, the scis confirmed certain energy transitions in quantum dots that had previously 1-ly been predicted theoretically: the so-called radiative auger process. for their investigations, the researchers in basel and copenhagen used spesh samples that the team from the chair of applied solid state physics at ruhr-universität bochum had produced. the researchers reprt their results inna journal nature nanotek, published online on 15 jun 2020.
lock up charge carriers
in order to create a quantum dot, the bochum researchers use self-organizing processes in crystal growth. inna process, they produce billions of nanomt-sized crystals of, for ex, indium arsenide. in these they can trap charge carriers, s'as a single electron. this construct is interesting for quantum communication cause information can be encoded w'da help of charge carrier spins. for this coding, tis necessary to be able to manipul8 and read the spin from the outside. during readout, quantum information can be imprinted inna'da polarization offa photon, for ex. this then carries the information further atta speed of lite and can be used for quantum information transfer.
this is why scis are interested, for ex, in wha’ exactly happens inna quantum dot when energy is irradiated from outside onto the artificial atom.
spesh energy transitions demonstrated
atoms consist offa +ly charged core which is surrounded by one or + negly charged electrons. when one electron inna atom has a high energy, it can reduce its energy by two well-known processes: inna 1st process the energy is released inna form offa single quantum of lite (a photon) na other electrons are unaffected. a 2nd possibility is an auger process, where the high energy electron gives all its energy to other electrons inna atom. this effect was discovered in 1922 by lise meitner and pierre victor auger.
bout a decade l8r, a third possibility s'been theoretically described by the physicist felix bloch: inna so-called radiative auger process, the excited electron reduces its energy by transferring it to both, a lite quantum and another electron inna atom. a semiconductor quantum dot resembles an atom in many aspects. however, for quantum dots, the radiative auger process had 1-ly been theoretically predicted sfar. now, the experimental observation s'been achieved by researchers from basel. together with their colleagues from bochum and copenhagen, the basel-based researchers dr. matthias löbl and professor richard warburton ‘ve envisaged the radiative auger process inna limit of just a single photon and one auger electron. for the 1st time, the researchers demonstrated the connection tween the radiative auger process and quantum optics. they show that quantum optics measurements w'da radiative auger emission can be us'das a tool for investigating the dynamics of the single electron.
applications of quantum dots
using the radiative auger effect, scis can also precisely determine the structure of the quantum mechanical energy lvls available to a single electron inna quantum dot. til now, this was 1-ly possible indirectly via calculations in combination with optical methods. now a direct proof s'been achieved. this helps to better cogg the quantum mechanical system.
in order to find ideal quantum dots for ≠ applications, ?s s'as the folloing ‘ve to be answered: how much time does an electron remain inna energetically excited state? wha’ energy lvls form a quantum dot? and how can this be influenced by means of manufacturing processes?
≠ quantum dots in stable environments
the group envisaged the effect not 1-ly in quantum dots in indium arsenide semiconductors. the bochum team of dr. julian ritzmann, dr. arne ludwig and professor andreas wieck also succeeded in producing a quantum dot from the semiconductor gallium arsenide. in both material systems, the team from bochum has achieved very stable surroundings of the quantum dot, which s'been decisive for the radiative auger process. for many yrs now, the group at ruhr-universität bochum s'been working onna optimal conditions for stable quantum dots.
original content at: www.scidaily.com…