Dresden 2020 – wissenschaftliches Programm

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PRV: Preisträgervorträge


PRV I: Preisträgervortrag

Montag, 16. März 2020, 13:15–13:45, HSZ 01

Quantum Dots for Quantum Technologies — •Dieter Bimberg — TU Berlin and CIOMP of CAS Changchun — Laureate of the Stern Gerlach Medal 2020

Universal self-organization at surfaces of semiconductors lead to the formation of coherent quantum dots (QDs). Their electronic and optical properties are close to those of atoms in a dielectric cage. Their delta-function density of states is only twofold degenerate [1]. All few particle states are strongly Coulomb-correlated due to the strong carrier localisation. Their energies depend on shape and size of the dots, such that positive, zero or negative biexciton binding energies and fine-structure splitting appear [2].

Applications of single, few and millions of QDs for novel Quantum Technologies will be demonstrated.

a. Single QDs can be emitters of Q-bits on demand or entangled photons for future quantum security systems. In electrically pumped RCLED structures, emission of q-bits at rates beyond 1 Gbit/s were shown [3, 4].

b. Hybridization of Flash and DRAMs, bringing together the advantages of both types of memories, is the “Holy Grail” of memories and ensures future memory development after the end of Moore’s law. The goal of non-volatility (i.e. storage time > 10 years) can be achieved for the storage of holes in type II (InGa)Sb QDs embedded in a (AlGa)P matrix [5].

c. The demand for higher data rates in optical networks, requires novel ultra-high bit rate energy efficient sources. QD Lasers based on GaAs emit up to the O-band at 1.3 µm, showing record low jth and complete temperature stability up to 80C. Passive mode-locking generates pulses in the sub-ps range at repetition rates up to 90 GHz. The hat spectrum of one single laser of several tens of closely spaced narrow lines is thus a potential pulse source for bit rates up to ≈ 6 TBit/s using DQPSK [6].

[1] M. Grundmann, O. Stier, D. Bimberg, Pyramidal Quantum Dots – Strain Distribution, Optical Phonons, and Electronic Structure, Phys. Rev. B 52, 11969 (1995); O. Stier, M. Grundmann, D. Bimberg, Electronic and optical properties of strained quantum dots modelled by 8-band k.p theory, Phys. Rev. B 59, 5688 (1999)

[2] S. Rodt, A. Schliwa, K. Pötschke, F. Guffarth, D. Bimberg, Correlation of structural and few particle properties of self-organized InAs/GaAs quantum dots, Phys. Rev. B 71, 155325 (2005)

[3] A. Schliwa, M. Winkelnkemper, A. Lochmann, E. Stock, D. Bimberg, (InGa)As/GaAs quantum dots grown on a (111) surface as ideal sources of entangled photon pairs, Phys. Rev. B 80, 601307(R) (2009)

[4] W. Unrau, D. Bimberg, Flying q-bits and entangled photons, Laser Photonics Review 8, 276 (Wiley, 2014)

[5] L. Bonato, F. I. Arikan, L. Desplanque, C. Coignon, X. Wallart, Yi Wang, P. Ruterana, D. Bimberg, Hole Localization Energy of 1.18 eV in GaSb quantum dots embedded in GaP, Phys. Stat. Sol (b) 10, 1877 (2016)

[6] G. Eisenstein, D. Bimberg (eds.), Green Photonics and Electronics (Springer, 2017)

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