Towards integration of GaAs quantum dots with superconducting waveguide and frequency conversion for quantum memories

Date

Jan 19, 2023

Time

9:00 AM - 10:00 AM

Speaker

Ankita Choudhary

Affiliation

IFW Dresden

Language

en

Main Topic

Materialien

Host

Kristina Krummer-Meier

Description

Envisioned future quantum communication networks promise a multitude of benefits such as ultra-low latency through quantum synchronization and fully secure data communication. One of the most important building blocks in order to realize these large-scale quantum networks are quantum memories. These quantum memories enable deterministic storage and on-demand retrieval of single bits of quantum information, i.e. qubits. GaAs quantum dots have proven to be excellent entangled photon pair sources but this system suffers from strong dephasing of its carrier spin qubits [1]. The quantum dot spin qubit coherence is limited due to their semiconductor environment via spin-orbit coupling to the magnetic moments of the atomic nuclei. On the other hand, diamond color centers are excellent quantum memories, 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 control of deterministically prepared spin states in order to minimize their decoherence. While the all-optical heralded preparation of spin states in GaAs 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 manipulation of quantum dot spin qubits via injection of microwave pulses by superconducting co-planar waveguide structures. This technique will allow us to achieve full control of the quantum dot spin qubit system. Another approach to achieving good quantum memories is by using color centers in diamond in combination with GaAs quantum dot based entangled photon sources. In order to realize this, the carriers of the quantum information, i.e. photons, need to be efficiently converted between the operating energies of quantum light source and memories without the loss of quantum information using quantum frequency conversion. Hence, we present quantum frequency conversion from of 780nm to 619nm, i.e. from GaAs quantum dot emission to the zero-phonon line of the diamond Sn vacancy center, using sum frequency generation in a periodically poled lithium niobate crystal and an infrared 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, Phys. Rev. Letter 119, 253601(2017) [3] C. Hopfmann et al, PRB 104, 75301 (2021). [4]. F. H. L. Koppens et al, PRL 100 (2008).

Links

• Seminars at the IFW

Last modified: Jan 19, 2023, 7:39:49 AM