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Recent advances in cavity quantum optomechanics have enabled breakthroughs such as ground state cooling of mechanical motion, observation of quantum backaction, standard quantum limit of position measurement and entanglement between optical and mechanical degrees of freedom [1]. Simultaneously, the upgraded version of current gravitational-wave interferometers is expected to suffer from optomechanical...
In forthcoming quantum networks various quantum systems might be involved to accomplish individual tasks, including storage of quantum states, quantum logic operations, error correction, or entanglement distillation. An interface between a single photon emitter and a potential photon storage could provide one fundamental building block of such a hybrid quantum system.
Quantum dots based on InAs/InP hold the promise to deliver entangled photons with wavelength suitable for the conventional telecom window around 1550 nm [1]. This makes them predestined to be used in future quantum networks applications based on existing fiber optics infrastructure. A prerequisite for the efficient generation of such entangled photons is a small fine structure splitting (FSS) in the...
The latest advances in the design and implementation of semiconductor sources of quantum light show their competence to efficiently deliver indistingishable single photons [1-3] or photon pairs with high degree of entanglement [4-5]. These achievements combined with the possibility of photon storage [6] show the potential of quantum dots to become building blocks of a quantum network.
The ability to transfer entanglement over large distance is a main requirement for quantum networks. Another fundamental ingredient is the storage of such a quantum state in a quantum memory. To this end a useful resource is a photon pair for which one photon is resonant with the memory while its partner is at a low-loss telecommunication wavelength. We recently presented a photon pair source, compatible...
Optical hybrid quantum information processing aims at mixing the traditionally separated discrete (DV) and continuous variable (CV) tools and concepts. In this approach, both DV states, such as single photons, and CV states, for example Schrödinger cats states: |cat ±〉 ∝ |α〉 ± | − α〉, are used. Having succeeded in experimentally generating hybrid entanglement of light for flying qubits [2], we will...
We are working on hybrid quantum information processing, which combines two methodologies of quantum information processing — qubit and continuous variable (CV) [1]. More precisely, we encode logical qubits by using CV methodology and utilize CV quantum processors for the realization of a fault-tolerant large-scale universal optical quantum computer. The advantage of this methodology is that we can...
Entangled photon pair is key factor for realization of quantum communication, quantum information, etc. For long distance quantum communication, it is necessary to generate narrow band biphoton for interaction with atomic based quantum memory. In recent years, generation of time-frequency entangled photon pairs based on spontaneous four-wave mixing (SFWM) process in atomic ensemble have been reported...
All-dielectric and semiconductor nonlinear nanophotonics is an emerging field enabling efficient optical interactions between magnetic and electric resonances at sub-wavelength scales, thereby achieving high directionality and high figures of merit due to very low losses [1, 2]. It was shown that AlGaAs nanodisks with quadratic nonlinear susceptibility can provide second harmonic generation (SHG)...
An efficient resource of entanglement in atom-photon-based quantum networks are polarization-entangled photon pairs generated by type-II spontaneous parametric down-conversion (SPDC). Compatibility in frequency and bandwidth between such photons and a single trapped 40Ca+-ion was first shown in [1]. The best SPDC entanglement values so far have been achieved by single-pass conversion in Sagnac configuration...
Spontaneous parametric down-conversion (SPDC), one of the most important nonlinear processes, is of paramount interest especially in the field of quantum optics due to its intrinsic capability in generating entangled photon pairs in different degree of freedoms (DoFs). The spatial distribution of the paired photons generated through SPDC process are highly influenced by different crystal parameters...
Entanglement based quantum communications and quantum networks are considered as fundamental resources to address the demand of secure communications. In this context, the architecture known as quantum relay plays a crucial role as it allows linking together independent communication channels each spanned by a pair of entangled photons. In particular, this scheme is particularly interesting for long...
Quantum entanglement leads to the most counterintuitive effects in physics and an important quantum resource which plays a central role in the field of quantum information and communication. Entanglement can be easily destroyed by the decoherence processes due to unwanted coupling with the environment. Such uncontrollable interaction introduces noise and transform for example maximally entangled states...
Quantum technology is a fundamentally new way of harnessing Nature and it has potential for a truly revolutionary innovation and promise the next generation of products with exciting and astounding properties that will affect our lives profoundly. They will have a great influence in defence, aerospace, energy and telecommunications sectors. If this process is to continue in the future, new, quantum...
Technologies are currently being developed that explicitly address individual quantum states and make use of the “strange” quantum properties, such as superposition and entanglement — commonly referred to as Quantum Technologies (QT). A number of QT start-up companies were founded over the last decade [1] and large global companies, including Google, IBM, Intel, Microsoft and Toshiba, have recently...
Single-photon subtracting operation plays important roles in photonic quantum information processing. For example, it enables distillation of entanglement, noiseless amplification of a quantum state, and enhancement of measurement precision. In particular, the non-Gaussian characteristic of the operation is essential for genuine speed-up and universality of continuous-variable quantum computing. Until...
Entanglement, a fundamental resource of quantum technologies, is a unique quantum mechanical attribute. In various systems it can be achieved in various individual degrees of freedom, however some of those systems are able to create entanglement in multiple degrees of freedom simultaneously: hyper-entanglement [1]. Here, we report on demonstration of polarization [2] and time-bin [3] hyper-entangled...
Photonic circuits represent a promising platform to perform quantum simulation of several different physical phenomena. Indeed, large progresses have been achieved in the last few years due to the technological advances enabled by integrated photonics, which allowed to achieve a significant increase in the size of the implemented systems. Notable examples of observed phenomena in integrated circuits...
With the rapid development of spatially-resolving single-photon detectors, spatially structured multidimensional entangled states start to play a key role in modern quantum science. In particular, they find extensive applications in emerging fields such as quantum imaging, holography, computation or quantum-enhanced metrology. Moreover, spatially-multiplexed schemes hold a promise to increase the...
Various applications in the rapidly growing field of quantum information science require reliable and effective quantum light sources. We observed superconducting proximity in semiconductor light-emitting diodes (Fig. 1). These hybrid structures were proposed by us as an efficient approach for generation of entangled photons, based on Cooper-pair luminescence in semiconductors, which does not require...
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