Quantum dots for photonic quantum information technology

Abstract

The generation, manipulation, storage, and detection of single photons play a central role in emerging photonic quantum information technology. Individual photons serve as flying qubits and transmit the relevant quantum information at high speed and with low losses, for example between individual nodes of quantum networks. Due to the laws of quantum mechanics, the associated quantum communication is fundamentally tap-proof, which explains the enormous interest in this modern information technology. On the other hand, stationary qubits or photonic states in quantum computers can potentially lead to enormous increases in performance through parallel data processing, to outperform classical computers in specific tasks when quantum advantage is achieved. In this review, we discuss in depth the great potential of semiconductor quantum dots in photonic quantum information technology. In this context, quantum dots form a key resource for the implementation of quantum communication networks and photonic quantum computers, because they can generate single photons on demand. Moreover, these solid-state quantum emitters are compatible with the mature semiconductor technology, so that they can be integrated comparatively easily into nanophotonic structures such as resonators and waveguide systems, which form the basis for quantum light sources and integrated photonic quantum circuits. After a thematic introduction, we present modern numerical methods and theoretical approaches to device design and the physical description of quantum dot devices. We then introduce modern methods and technical solutions for the epitaxial growth and for the deterministic nanoprocessing of quantum devices based on semiconductor quantum dots. Furthermore, we highlight the most promising device concepts for quantum light sources and photonic quantum circuits that include single quantum dots as active elements and discuss applications of these novel devices in photonic quantum information technology. We close with an overview of open issues and an outlook on future developments.

Assessing the Alignment Accuracy of State-of-the-Art Deterministic Fabrication Methods for Single Quantum Dot Devices

“…Solid-state single-photon emitters are crucial building blocks for developing efficient quantum light sources and on-chip quantum circuits for quantum information processing platforms. Self-assembled semiconductor quantum dots (QDs) are one of the most promising solid-state quantum emitters for realizing quantum communication networks, − and photonic quantum computation − which will enable many applications in photonic quantum technologies . Here, one uses the fact that a single QD efficiently emits single photons due to its quantized two-level electronic structure.…”

“…Self-assembled semiconductor quantum dots (QDs) are one of the most promising solid-state quantum emitters for realizing quantum communication networks, 1−3 and photonic quantum computation 4−6 which will enable many applications in photonic quantum technologies. 7 Here, one uses the fact that a single QD efficiently emits single photons due to its quantized two-level electronic structure. However, extracting and collecting the emitted photons for useable application is rather challenging, and in a simple planar device geometry, most of the photons are restrained in the semiconductor matrix due to total internal reflection.…”

Control of Quantized Spontaneous Emission from Single GaAs Quantum Dots Embedded in Huygens’ Metasurfaces

“…We expect that the combination of semiconductor metasurfaces with embedded LDE QD emitters will facilitate unexplored multiple quantum emitter phenomena with the potential for novel quantum sensing and communication technologies. 1,52 ■ METHODS Epitaxial Growth. The sample described in this study is grown using molecular beam epitaxy (MBE) on a semiinsulating GaAs (100) substrate (VA1166).…”

“…Research into on-demand, single and entangled photon sources for all areas of quantum information processing has been actively pursued for the past several decades. − The development of these sources has evolved in parallel using parametric processes, , and a variety of single photon emitters − coupled to engineered photonic structures. , For the latter type, epitaxial quantum dots (QDs) offer clear advantages, such as wavelength tunable emission, on demand operation, high brightness, high degree of indistinguishability, versatility in entangling photons to other degrees of freedom such as spin, , and finally, monolithic integration with photonic cavities or other photonic circuits. − Among epitaxial QDs, local-droplet-etched (LDE) epitaxy QDs are particularly attractive as they form a deeper confinement potential compared to Stranski–Krastanov (S–K) QDs and offer a greater freedom in choosing the dot and host material composition and their areal density, smaller fine structure splitting of the neutral exciton providing a path to wider emission tunability and integration. − …”

Intermediate Field Coupling of Single Epitaxial Quantum Dots to Plasmonic Waveguides

“…Quantum photonics has the potential to revolutionize our world with breakthrough technologies such as quantum computing and quantum communication, for instance, using quantum dots (QDs) as single-photon emitters . Especially in terms of applications, scalability is indispensable, and integrated photonic networks are highly sought after .…”