Towards a Distributed Quantum Computing Ecosystem

The Quantum Internet, by enabling quantum communications among remote quantum nodes, is a network capable of supporting functionalities with no direct counterpart in the classical world. Indeed, with the network and communications functionalities provided by the Quantum Internet, remote quantum devices can communicate and cooperate for solving challenging computational tasks by adopting a distributed computing approach. The aim of this paper is to provide the reader with an overview about the main challenges and open problems arising with the design of a Distributed Quantum Computing ecosystem. For this, we provide a survey, following a bottom-up approach, from a communications engineering perspective. We start by introducing the Quantum Internet as the fundamental underlying infrastructure of the Distributed Quantum Computing ecosystem. Then we go further, by elaborating on a high-level system abstraction of the Distributed Quantum Computing ecosystem. Such an abstraction is described through a set of logical layers. Thereby, we clarify dependencies among the aforementioned layers and, at the same time, a road-map emerges

Quantum Internet: from Communication to Distributed Computing!

In this invited paper, the authors discuss the exponential computing speed-up achievable by interconnecting quantum computers through a quantum internet. They also identify key future research challenges and open problems for quantum internet design and deployment.Comment: 4 pages, three figures, invited pape

Quantum Switch for the Quantum Internet: Noiseless Communications through Noisy Channels

Counter-intuitively, quantum mechanics enables quantum particles to propagate simultaneously among multiple space-time trajectories. Hence, a quantum information carrier can travel through different communication channels in a quantum superposition of different orders, so that the relative time-order of the communication channels becomes indefinite. This is realized by utilizing a quantum device known as quantum switch. In this paper, we investigate, from a communication-engineering perspective, the use of the quantum switch within the quantum teleportation process, one of the key functionalities of the Quantum Internet. Specifically, a theoretical analysis is conducted to quantify the performance gain that can be achieved by employing a quantum switch for the entanglement distribution process within the quantum teleportation with respect to the case of absence of quantum switch. This analysis reveals that, by utilizing the quantum switch, the quantum teleportation is heralded as a noiseless communication process with a probability that, remarkably and counter-intuitively, increases with the noise levels affecting the communication channels considered in the indefinite-order time combination.Comment: 14 pages, double colum

Capacity Bounds for Quantum Communications through Quantum Trajectories

In both classical and quantum Shannon's information theory, communication channels are generally assumed to combine through classical trajectories, so that the associated network path traversed by the information carrier is well-defined. Counter-intuitively, quantum mechanics enables a quantum information carrier to propagate through a quantum trajectory, i.e., through a path such that the causal order of the constituting communications channels becomes indefinite. Quantum trajectories exhibit astonishing features, such as providing non-null capacity even when no information can be sent through any classical trajectory. But the fundamental question of investigating the ultimate rates achievable with quantum trajectories is an open and crucial problem. To this aim, in this paper, we derive closed-form expressions for both the upper- and the lower-bound on the quantum capacity achievable via a quantum trajectory. The derived expressions depend, remarkably, on computable single-letter quantities. Our findings reveal the substantial advantage achievable with a quantum trajectory over any classical combination of the communications channels in terms of ultimate achievable communication rates. Furthermore, we identify the region where a quantum trajectory incontrovertibly outperforms the amount of transmissible information beyond the limits of conventional quantum Shannon theory, and we quantify this advantage over classical trajectories through a conservative estimate

Speeding up Future Video Distribution via Channel-Aware Caching-Aided Coded Multicast

Future Internet usage will be dominated by the consumption of a rich variety of online multimedia services accessed from an exponentially growing number of multimedia capable mobile devices. As such, future Internet designs will be challenged to provide solutions that can deliver bandwidth-intensive, delay-sensitive, on-demand video-based services over increasingly crowded, bandwidth-limited wireless access networks. One of the main reasons for the bandwidth stress facing wireless network operators is the difficulty to exploit the multicast nature of the wireless medium when wireless users or access points rarely experience the same channel conditions or access the same content at the same time. In this paper, we present and analyze a novel wireless video delivery paradigm based on the combined use of channel-aware caching and coded multicasting that allows simultaneously serving multiple cache-enabled receivers that may be requesting different content and experiencing different channel conditions. To this end, we reformulate the caching-aided coded multicast problem as a joint source-channel coding problem and design an achievable scheme that preserves the cache-enabled multiplicative throughput gains of the error-free scenario,by guaranteeing per-receiver rates unaffected by the presence of receivers with worse channel conditions.Comment: 11 pages,6 figures,to appear in IEEE JSAC Special Issue on Video Distribution over Future Interne

Deterministic Generation of Multipartite Entanglement via Causal Activation in the Quantum Internet

Entanglement represents ``\textit{the}'' key resource for several applications of quantum information processing, ranging from quantum communications to distributed quantum computing. Despite its fundamental importance, deterministic generation of maximally entangled qubits represents an on-going open problem. Here, we design a novel generation scheme exhibiting two attractive features, namely, i) deterministically generating different classes -- namely, GHZ-like, W-like and graph states -- of genuinely multipartite entangled states, ii) without requiring any direct interaction between the qubits. Indeed, the only necessary condition is the possibility of coherently controlling -- according to the indefinite causal order framework -- the causal order among the unitaries acting on the qubits. Through the paper, we analyze and derive the conditions on the unitaries for deterministic generation, and we provide examples for unitaries practical implementation. We conclude the paper by discussing the scalability of the proposed scheme to higher dimensional genuine multipartite entanglement (GME) states and by introducing some possible applications of the proposal for quantum networks

NUOVI BIOMARKERS PREDITTIVI NELL'IDROSADENITE SUPPURATIVA: DALLA PROFILAZIONE METABOLICA ALLA STRATIFICAZIONE PROGNOSTICA

Background: L'importanza dei disordini metabolici nei pazienti affetti da Idrosadenite Suppurativa (IS), tendenzialmente giovani, ma già gravati da un ventaglio di comorbidità potenzialmente gravi, impone la necessità di valutare l'utilità di specifici biomarkers, particolarmente in risposta ad una terapia con un anti-TNF-alpha (adalimumab), unico farmaco biologico attualmente approvato per l'utilizzo label in pazienti con forme gravi e resistenti di questa dermatosi. Irisina e mTOR si prestano, per le loro caratteristiche, a fungere da attendibili biomarkers in questa particolare categoria di pazienti, sia in fase di profilazione metabolica che di stratificazione prognostica. Obiettivi: Analizzare l'effetto del blocco selettivo del TNF-α sull'assetto metabolico di pazienti con IS e l'eventuale correlazione con la risposta clinica alla terapia stessa, mediante l'utilizzo di specifici biomarkers (irisina e mTOR), noti come possibili indicatori predittivi di disordini metabolici incipienti. Materiali e Metodi: Sono stati arruolati 30 pazienti, affetti da idrosadenite suppurativa resistente alle terapie convenzionali e candidati alla terapia con adalimumab. Al momento dell'arruolamento (W0) e dopo 16 settimane di terapia con adalimumab (W16) tutti i pazienti sono stati sottoposti ad una fenotipizzazione clinica e metabolica. In tutti i pazienti arruolati è stato eseguito lo studio in vivo su campioni ematici per la valutazione dei livelli circolanti di irisina e, in un sottogruppo di 13 pazienti è stato anche eseguito lo studio ex vivo su campioni bioptici da cute lesionale e non lesionale per la valutazione del pathway di mTOR. Risultati: Nella fase in vivo dello studio abbiamo evidenziato come i livelli plasmatici di irisina siano significativamente più bassi nei pazienti affetti da IS alla baseline rispetto ai controlli sani e come i livelli della adipomiochina risultavano significativamente aumentati dopo 16 settimane di terapia con adalimumab rispetto al basale (W-0) (p <0,001). Tale incremento, inoltre, risultava direttamente correlato all'entità della risposta clinica. Lo studio ex vivo ha dimostrato una espressione del gene mTOR significativamente aumentata alla baseline (W0) nonché una significativa riduzione della stessa dopo 16 settimane (W16) di terapia con Adalimumab, suggerendo la stretta relazione tra TNF-α e pathaway di mTOR. Anche in questo caso la riduzione era direttamente correlata all'entità della risposta clinica nei pazienti responder e non responder. Conclusioni: Il nostro studio dimostra come nell'IS una terapia in grado di bloccare selettivamente una citochina infiammatoria come il TNF-α possa indirettamente influenzare anche i livelli sierici di irisina e l'espressione genica di mTOR, entrambi coinvolti nell'omeostasi metabolica. Inoltre, la dimostrazione della diretta correlazione tra responsività clinica dei pazienti trattati e capacità della terapia di modificare i livelli dei biomarkers in esame, costituisce una possibile base per studi futuri

Photodynamic therapy: a treatment tool for hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, recurrent, debilitating inflammatory disease of unknown aetiology. The current standard of care for HS includes antibiotics (oral/topical), retinoids (oral/topical) and intralesional steroids. However, the recurrence of the disease and the unsuccessful of the different treatments stimulate findings of different therapy using light source. Among these, photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) has been proposed by some authors recently. In this study we report the experience of 15 patients affected by HS resistant to conventional therapy treated with ALA-PDT