Optical charge injection and coherent control of a quantum-dot spin-qubit emitting at telecom wavelengths

Abstract

Solid-state quantum emitters with manipulable spin-qubits are promising platforms for quantum communication applications. Although such light-matter interfaces could be realized in many systems only a few allow for light emission in the telecom bands necessary for long-distance quantum networks. Here, we propose and implement an optically active solid-state spin-qubit based on a hole confined in a single InAs/GaAs quantum dot grown on an InGaAs metamorphic buffer layer emitting photons in the C-band. We lift the hole spin-degeneracy using an external magnetic field and demonstrate hole injection, initialization, read-out and complete coherent control using picosecond optical pulses. These results showcase a solid-state spin-qubit platform compatible with preexisting optical fiber networks.

Multiple Rabi rotations of trions in InGaAs quantum dots observed by photon echo spectroscopy with spatially shaped laser pulses

“…The signal in HVH rather follows a polynomial function of higher degree in the low power range indicating that another powerdependent contribution leads to an increase of the trion signal. We associate this finding with a photo-charging of the QDs [24,25]. Increasing the optical power thus induces a rising of the number of singly charged QDs.…”

Epitaxial quantum dots: a semiconductor launchpad for photonic quantum technologies

“…5(a), bottom panel]. This rotation can be understood by the ac Stark effect induced by the strong laser [105,166–172] ; the spin is rotated along a certain in-plane axis in the Bloch sphere, usually defined as the x axis, by an arbitrary polar angle θ. Another method to rotate the electron spin relies on two phase-locked laser pulses, which are likewise far-red detuned from the excited spin states.…”

“…Internal conversion efficiencies of 5%–15% have been demonstrated in the silicon waveguides [303,304] and 12%–60% in micro-resonators [305–307] , where the limitation is mainly the phase mismatch. An alternative approach is to develop high-quality quantum dots directly at telecom wavelengths [69,107,172,283,308–310] . In this approach, losses due to wavelength conversion can be circumvented.…”

“…By tailoring the growth process, InAs quantum dots on a GaAs substrate can also emit at the telecom O-band or C-band [308,309] . These telecom quantum dots create single photons and entangled photon pairs just like their shorter-wavelength counterpart; fine-structure erasure [309] and electron-spin manipulation [172] have also been demonstrated. Moving forward requires improving the optical qualities of telecom quantum dots-one way is to implement the charge control by electric gating [51] .…”

Coherent light scattering from a telecom C-band quantum dot

“…For emission in the telecom C-band, quantum dot (QD) technology has been most prominent so far [8], where two different material systems, modified InAs/GaAs and InAs/InP based, respectively, have been pursued [9,10]. These systems have made leaps in their development recently, maturing from showing evidence of single photon emission [11,12] to demonstrations of entangled photon emission [13,14] and the development of a spin-photon interface [15].…”