Physics Colloquium on Jan. 23, 2023: Challenges Towards High Efficiency Low Noise Quantum Dot Single Photon Sources.

20.01.23 | Physics Colloquium, Event

On Monday (23.01.2023) at 12.00 pm c.t. the next date of our Physics Colloquium will take place.

Speaker is Dr. Arne Ludwig (RUB) on the topic: "Challenges Towards High Efficiency Low Noise Quantum Dot Single Photon Sources."

A key component for photonic quantum devices is a source of high-fidelity photonic qubits, a single photon source (SPS) [1]. A promising route to create such a device employs semiconductor quantum dots (QDs) in photonic cavities. These QDs behave like artificial atoms displaying fully quantized electronic states. Moreover, the exquisite toolbox of semiconductors, in particular scalable manufacturing is at hand. However, noise processes hamper solid state emitters [2]. A main contributor to decoherence and low efficiency is random charge rearrangements in the semiconductor environment or the QD itself. A random change of the QD's charge state from e.g. Auger processes [3] or photoionization [4] can switch the emitter temporarily off [3,5]. Noise from a fluctuating electrostatic environment is called charge noise. One way to efficiently suppress this, is to embed the QDs in the high purity material undoped region of a p-i-n-diode tunnel-coupled to a charge reservoir [6,7]. Following this approach, a highly efficient fiber-coupled SPS with an end-to-end efficiency of 57% has been developed [8].

We found a method to periodically modulate the density of QDs [9]. This recent progress in understanding epitaxial growth finalizes the presentation.


[1] P. Senellart et al, Nat Nano 12, 1026 (2017).

[2] A.V. Kuhlmann et al, Nat Phys 9, 570 (2013).

[3] A. Kurzmann et al, Nano Lett 16, 3367 (2016).

[4] P. Lochner et al, Phys. Rev. B 103, 075426 (2021).

[5] G. Gillard et al, npj Quantum Inf 7, 43 (2021).

[6] D. Najer et al, Nature 575, 622 (2019).

[7] L. Zhai et al, Nat Commun 11, 4745 (2020).

[8] N. Tomm et al, Nat Nano 16, 399 (2021).

[9] N. Bart et al, Nat Commun 13, 1633 (2022).

Abstract lecture Dr. Arne Ludwig

The introduction will be given by Prof. Dr. Ilya Eremin.

The faculty cordially invites all interested parties. The event will take place in lecture hall HNC 10 and hybrid via Zoom. Before the colloquium we offer coffee and cookies. This link will take you to the Zoom event (meetingID: 632 5520 9938, password: 526977). All dates of the Physics Colloquium can be found here.

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