Photonics for Quantum (PfQ)

Quantum-dot single photon source performance with quasi-coherent excited state preparation schemes

Gavin Crowder, Lora Ramunno, Stephen Hughes

Published Aug 2, 2024• 1 citation

Abstract

The preparation of quantum-dot qubits in the excited state is an integral part of the performance of an on-demand single photon source. Recent excitation schemes strategically use pulses that avoid spectral overlap with the qubit emission for easier differentiation between the pump and signal. In this work, we look at the robustness of two such pumping schemes, (i) a dichromatic pulse, and (ii) a notch-filtered adiabatic rapid passage (NARP) approach, in the presence of phonon coupling. We find that due to large instantaneous pulse strengths, the dichromatic pulse suffers from phonon-induced pure dephasing and can have up to 50% worse performance as a single photon source. On the other hand, the NARP approach is more robust against the phonon coupling due to a weaker and smoother pulse profile.

DOI: 10.1117/12.3026974

Related papers

Quantum-dot single-photon-source performance with off-resonant pulse preparation schemes

Gavin Crowder, Lora Ramunno, Stephen Hughes

The preparation of photonic qubits in the excited state is an integral part of the performance of an on-demand single photon source (SPS). Conventional resonant excitation, an excellent approach to maximize the coherence and indistinguishability of the SPS, often requires polarization filtering to remove the pump signal and isolate the qubit emission, but this results in an inherent 50\% hit to the efficiency. Recent excitation schemes strategically try to exploit pulses that excite the qubit while avoiding spectral overlap to bypass this required filtering. In this work, we compare three such pumping schemes to quantify the important SPS figures-of-merit for off-resonant quantum dot schemes, using: (i) a symmetrically detuned dichromatic pulse, (ii) a notch-filtered adiabatic rapid passage (NARP) pulse, and (iii) a swing up of the quantum emitter population (SUPER) pulse. Due to large instantaneous pulse strengths, the dichromatic pulse suffers from phonon-induced dephasing which can lower the SPS performance by up to 50\%. In contrast, the NARP and SUPER pulses are shielded from phonon coupling to differing degrees but both maintain excellent SPS performance. The SUPER pulse can lose significant efficiency if there is variance in its constituent pulses' amplitude, pulse width, or frequency, while the NARP pulse, though potentially more difficult to realize in experiments, is robust against variance in the pulse preparation.

arXiv:2511.00243Physical Review AFeb 9, 20261 citation

Ultra-fast spectroscopy on single self-assembled quantum dots with rapid adiabatic passage

Timo Kaldewey

Self-assembled semiconductor quantum dots are often referred to as artificial atoms. They are bright single photon sources implemented in an environment easier scalable then implementations with single atoms. These properties promote quantum dots as promising candidates for quantum information technology. A high fidelity state preparation reduces the error rate in quantum information protocols and is hence an essential requirement. \n \nIn this thesis the technique of rapid adiabatic passage is implemented with ultra-fast pulse parameters and is used to study single self-assembled quantum dots by detecting the resonance fluorescence signal following an optical excitation. Different experimental schemes provide insights into different aspects of a quantum dot and its environment. \n \nThe negative trion transition in a single quantum dot represents a good approach to creating an ideal two-level system. With this two-level system, the interaction of the electron trapped in the QD and phonons in the host material is studied with a single chirped pulse. Measuring the resonance fluorescence response of the quantum dot as a function of the pulse area for a set of chirp parameters reveals the electron-phonon interaction. Phonons in the semiconductor environment are a source of decoherence. The non-monotonic behaviour of the coupling to phonons is experimentally demonstrated. Furthermore, a decoupling regime where the electron oscillation is too fast for phonons to follow is reached. A high fidelity state preparation with a vanishing coupling to phonons is demonstrated. Experimental results are affirmed with an excellent agreement with simulations. \n \nIn another scheme, a three-level system consisting of the crystal ground state of the quantum dot, the neutral exciton and the biexciton is investigated. The goal in this experiment is a coherent, resonant and high fidelity preparation of a biexciton state robust against system parameter fluctuations. A biexciton in a semiconductor quantum dot is a source of polarization-entangled photons with high potential for implementation in scalable systems. An excitation with chirped pulses applying the technique of rapid adiabatic passage is the key for the biexciton preparation scheme. In contrast to other state of the art techniques, an interaction with phonons is here intentionally minimized reducing the dephasing and maintaining at the same time a robustness with respect to pulse area and detuning. A fidelity close to one is reached over a pulse area range of more than π. Also in this case, the interpretation of the experiment is confirmed by an excellent agreement with simulations which include a microscopic coupling to phonons. \n \n \nIn a third experiment, a sequence of two chirped pulses with different point spread functions is used to overcome the diffraction limit in spectroscopy. A universal technique - optical nanoscopy via quantum control - to perform diffraction-unlimited spectroscopy on two-level systems is presented. A model for simulating the system is developed and gives a prediction for the expected spatial resolution as a function of the pulse parameters. The concept is demonstrated and the prediction is fulfilled on self-assembled semiconductor quantum dots. A resolution down to 30 nm with an excitation wavelength of 950 nm is reached.

Jan 1, 20160 citations

Dynamical and Emission Properties of Quantum Emitters driven by Ultra-Short Laser Pulses

Juan E. Ardila-García, Juan S. Sierra-Jaraba, Herbert Vinck-Posada

The development of high-performance quantum technologies relies on the ability to prepare the quantum states of solid-state emitters with high fidelity while cleanly separating the emitted photons from the driving field. Here, we present a comprehensive theoretical comparison of three single-pulse coherent control protocols: resonant Rabi oscillations, adiabatic rapid passage (ARP), and notch-filtered ARP (NARP). To establish an ideal performance baseline, we first map the parameter spaces for each protocol in a closed system, identifying the regions of robust population inversion. We then use a Lindblad master equation to compute the time-resolved emission spectra in the presence of decoherence. Our results show that while all three schemes can generate identical, transform-limited Lorentzian photons, NARP uniquely combines the high-fidelity robustness of adiabatic passage with intrinsic spectral separability. Our findings, which align with the work on NARP by Wilbur et al., establish a clear design framework for engineering the next generation of quantum light sources.

arXiv:2507.17076Jul 22, 20251 citation

Notch-filtered adiabatic rapid passage for optically driven quantum light sources

Grant R. Wilbur, Ali Binai-Motlagh, A. Clarke +6 more

We present a driving scheme for solid-state quantum emitters, referred to as Notch-filtered Adiabatic Rapid Passage (NARP), that utilizes frequency-swept pulses containing a spectral hole resonant with the optical transition in the emitter. NARP enables high-fidelity state inversion and exhibits robustness to variations in the laser pulse parameters, benefits that are derived from the insensitivity of the condition for adiabatic evolution. NARP also offers the advantage of immunity to phonon-mediated excitation-induced dephasing when positively chirped control pulses are used. Our resonant driving approach could be combined with spectral filtering of the scattered pump light and photonic devices for enhanced collection efficiency to realize simultaneous high indistinguishability and brightness in single photon source applications.

APL PhotonicsOct 17, 202220 citations

Multi-NARP laser driving scheme for multiplexed quantum networks

Ali Binai-Motlagh, Grant R. Wilbur, Nour Allam +5 more

We extend the recently developed Notch-filtered Adiabatic Rapid Passage (NARP) scheme for laser-triggered single-photon sources to the simultaneous excitation of multiple emitters with varying transition energies, laying the groundwork for wavelength-division multiplexing in quantum optical networks. Our multi-NARP scheme does not rely on polarization filtering and thus enables the near-unity extraction efficiency of single photons from each quantum dot. Our approach also offers the advantages of robustness to variations in the laser pulse parameters and immunity to excitation-induced dephasing tied to electron–phonon coupling. We show that simultaneous triggering of at least 10 emitters is possible, enabling the development of high-bandwidth quantum networks.

Optica QuantumSep 18, 20252 citations

Quantum State Preparation Using Chirped Laser Pulses in Semiconductor Quantum Dots

Ajan P. Ramachandran

A quantum emitter (QE) is a physical system that can be used to encode a quantum state via some internal degree of freedom (e.g. exciton, electron spin, valley) and is coupled to light via a dipolar transition that enables the conversion of that quantum state into the state of a photon and vice versa. Such QEs can be applied to sources of single and entangled photons for applications in quantum cryptography or quantum imaging and a collection of coupled QEs can be used to realize a small quantum simulator or quantum memory node in a distributed quantum network. Among solid state QE systems, semiconductor quantum dots (QD) are particularly attractive due to their high radiative quantum efficiencies, their strong optical coupling, enabling fast and arbitrary qubit rotations, and their tunable emission in the range of standard telecommunication wavelengths. Adiabatic rapid passage (ARP) is a state preparation scheme that enables the excitation and de-excitation of a QE with a high fidelity even in the presence of fluctuations in experimental parameters such as intensity and frequency of the control laser pulse. This excitation scheme may be used for quantum state initialization in quantum information platforms and for triggering quantum light sources. This thesis work concerns an exploration of the efficacy of ARP for the quantum control of excitons in semiconductor QDs. The experiments carried out in this work show that the impact of phonons may be suppressed for ARP, pointing to the possibility of high-fidelity inversion at elevated temperatures. We also investigate the dependence of the threshold for decoherence suppression on the size and shape of the QD. The experiments performed in this thesis work also quantify the detuning tolerance of ARP. ARP was also used to demonstrate parallel quantum state initialization in two different QDs with different transition energies and dipole moments.

May 21, 20200 citations