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UID:DSC-19379
DTSTART;TZID=Europe/Berlin:20230119T090000
SEQUENCE:1674110389
TRANSP:OPAQUE
DTEND;TZID=Europe/Berlin:20230119T100000
URL:https://www.dresden-science-calendar.de/calendar/en/detail/19379
LOCATION:IFW\, Helmholtzstraße 2001069 Dresden
SUMMARY:Choudhary: Towards integration of GaAs quantum dots with supercondu
 cting waveguide and frequency conversion for quantum memories
CLASS:PUBLIC
DESCRIPTION:Speaker: Ankita Choudhary\nInstitute of Speaker: IFW Dresden\nT
 opics:\n\n Location:\n  Name: IFW (A1E.10\, Hörsaal\, IFW Dresden)\n  Str
 eet: Helmholtzstraße 20\n  City: 01069 Dresden\n  Phone: \n  Fax: \nDescr
 iption: Envisioned future quantum communication networks promise a multitu
 de of benefits such as ultra-low latency through quantum synchronization a
 nd fully secure data communication. One of the most important building blo
 cks in order to realize these large-scale quantum networks are quantum mem
 ories. These quantum memories enable deterministic storage and on-demand r
 etrieval of single bits of quantum information\, i.e. qubits. GaAs quantum
  dots have proven to be excellent entangled photon pair sources but this s
 ystem suffers from strong dephasing of its carrier spin qubits [1]. The qu
 antum dot spin qubit coherence is limited due to their semiconductor envir
 onment via spin-orbit coupling to the magnetic moments of the atomic nucle
 i. On the other hand\, diamond color centers are excellent quantum memorie
 s\, but not ideal entangled photon pair sources [2]. In order to obtain an
  efficient quantum memory system for long distance quantum communication\,
  we focus on two approaches.  The first solution is to achieve full contro
 l of deterministically prepared spin states in order to minimize their dec
 oherence. While the all-optical heralded preparation of spin states in GaA
 s quantum dots has been demonstrated by us [3]\, extended coherence times 
 may be achieved by coherent manipulation of the spin states using the spin
  echo technique [4]. Furthermore\, our goal is to enable coherent manipula
 tion of quantum dot spin qubits via injection of microwave pulses by super
 conducting co-planar waveguide structures. This technique will allow us to
  achieve full control of the quantum dot spin qubit system. Another approa
 ch to achieving good quantum memories is by using color centers in diamond
  in combination with GaAs quantum dot based entangled photon sources. In o
 rder to realize this\, the carriers of the quantum information\, i.e. phot
 ons\, need to be efficiently converted between the operating energies of q
 uantum light source and memories without the loss of quantum information u
 sing quantum frequency conversion. Hence\, we present quantum frequency co
 nversion from of 780nm to 619nm\, i.e. from GaAs quantum dot emission to t
 he zero-phonon line of the diamond Sn vacancy center\, using sum frequency
  generation in a periodically poled lithium niobate crystal and an infrare
 d laser pump of about 3 µm wavelength. Preliminary results indicate that 
 a conversion efficiency of at least 25% can be achieved.   References [1] 
 l. Cywinski\, Acta Phys. Pol. A 119\, 576 (2011) [2] T. Iwasaki et al\, Ph
 ys. Rev. Letter 119\, 253601(2017) [3] C. Hopfmann et al\, PRB 104\, 75301
  (2021). [4]. F. H. L. Koppens et al\, PRL 100 (2008).
DTSTAMP:20260712T195822Z
CREATED:20230105T064019Z
LAST-MODIFIED:20230119T063949Z
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