44 research outputs found
Experimental Generation of Robust Entanglement from Classical Correlations via Local Dissipation
No full textWe experimentally show how classical correlations can be turned into quantum entanglement, via the presence of dissipation and the action of a CNOT gate. We first implement a simple two-qubit protocol in which entanglement production is not possible in the absence of such kind of noise, while it arises with its introduction, and is proportional to its amount. We then perform a more elaborate four-qubit experiment, by employing two hyperentangled photons initially carrying only classical correlations. We demonstrate a scheme where the entanglement is generated via local dissipation, with the advantage of being robust against local unitaries performed by an adversary
Structure of multipartite entanglement in random cluster-like photonic systems
Get PDFQuantum networks are natural scenarios for the communication of information among distributed parties, and the arena of promising schemes for distributed quantum computation.Measurement-based quantum computing is a prominent example of how quantum networking,embodied by the generation of a special class of multipartite states called cluster states, can be usedto achieve a powerful paradigm for quantum information processing. Here we analyze randomly generated cluster states in order to address the emergence of correlations as a function of the density of edges in a given underlying graph. We find that the most widespread multipartite entanglement does not correspond to the highest amount of edges in the cluster. We extend the analysis to higher dimensions, finding similar results, which suggest the establishment of small world structures in the entanglement sharing of randomised cluster states, which can be exploited in engineering more efficient quantum information carrier
Exploiting path-polarization hyperentangled photons for multiqubit quantum information protocols
Get PDFIn this thesis we describe and exploit a photonic source of hyperentangled states which allows the creation of a four qubit entangled state using path and polarization of two photons; this will be the main resource for a series of experiments that are linked to the main goal of exploring the advantages that quantum correlations brings in the aforementioned tasks. In particular we will focus onto showing that the same correlations which define the \emph{quantumness} of a state can be interpreted in two very different ways: either as something that introduces \emph{non-locality} between qubits, or something which reduces the \emph{information entropy} between qubits. Both interpretations allow the definition and observation of quantum advantage but, as we will show, the two views are not completely equivalent.
Our goal will be showing that quantum correlations can be seen as \emph{currency} that can be spent to perform tasks more efficiently than in the classical case
Experimental extractable work-based multipartite separability criteria
Get PDFA thermodynamic theory of quantum entanglement as well as the establishment of rigorous formal connections between the laws of thermodynamics and the phenomenology of entanglement are currently open areas of investigation. In this quest, a core problem is embodied by the understanding of the role that entanglement plays in processes of work extraction. Here, by considering information thermodynamics-based protocols, we answer the question “Is it possible to infer, quantitatively, quantum correlations by considering work-extraction schemes?”. Our experimental settings consist of suitably designed multi-photon optical interferometers able to address the case of both bipartite and multipartite entangled states. We compare the performance of such criteria to that of witnesses of entanglement based on the violation of Bell-like tests, showing their inherently different nature. Our work contributes strongly to the ongoing efforts in establishing photonic systems as a platform for experiments in information thermodynamics
Experimental lower bounds to the classical capacity of quantum channels
No full textWe show an experimental procedure to certify the classical capacity for noisy qubit channels. The method makes use of a fixed bipartite entangled state, where the system qubit is sent to the channel input and the set of local measurements, σx - σx, σy - σy, and σz - σz, is performed at the channel output and the ancilla qubit, thus without resorting to full quantum process tomography. The witness to the classical capacity is then achieved by reconstructing sets of conditional probabilities, noise deconvolution, and classical optimization of the pertaining mutual information. The performance of the method to provide lower bounds to the classical capacity is tested by a two-photon polarization entangled state in Pauli channels and amplitude damping channels. The measured lower bounds to the channels are in high agreement with the simulated data, which take into account both the experimental entanglement fidelity F=0.979±0.011 of the input state and the systematic experimental imperfections
Maxwell’s Demon in Photonic Systems
No full textPhotons are massless, noninteracting particles, and thermodynamics seems to be completely inappropriate in their description. Here we present two examples of the opposite: connecting thermodynamics with information through Maxwell’s Demon provides interesting insight on properties of light fields. This does not amount to directly applying thermodynamics to photons, but rather helps to obtain tools and concepts from thermodynamics to manipulate and evaluate the information content of light. The examples presented here pinpoint some of the challenges that arise when putting a thought experiment into practice and provide new insights into the relation between thermodynamic work and information
Notes on the inscribed Old and Middle Kingdom coffins in the Egyptian Turin Museum
No full textThe Turin collection of the coffins of the Old and Middle Kingdom, subject of a project of research by the author, mainly derives from the digging of Ernesto Schiaparelli at Asyut, Qaw el-Kebir and Gebelein at the beginning of the 20th century. The analysis of the materials offers several suggestions for a funerary tradition, which covers the period between the end of the Old Kingdom and the Middle Kingdom; at the same time, the textual collection is coherent with these traditions, that go to be the main features of the funerary culture of the Middle Kingdom. Among the others, some topics of the research are here exposed:
- Archaeological context: these coffins confirm the prestige of the necropolis investigated by E. Schiaparelli.
- Textual data: due to the origin of the coffins, the Turin collection offers some case-studies of the funerary doctrine between the Old and Middle Kingdom. The diffusion of the Coffin Texts, well known by the textual collection from the coffins of Iqer from Gebelein, is confirmed by other unpublished sources, mainly from Asyut.
- Epigraphical data from First Intermediate Period and Middle Kingdom scribal traditions
Hyperentangled photon states on a chip
No full textIn order to achieve an optimal scalability, stability and compactness of complex quantum optical schemes based on a large number of elements, waveguide technology is of fundamental importance. Lately this technique has been implemented with experimental success with the introduction in the quantum domain of photonic integrated circuits built in various platforms and materials [1
Quantifying protocol efficiency: a thermodynamic figure of merit for classical and quantum state-transfer protocols
Get PDFManipulating quantum systems undergoing non-Gaussian dynamics in a fast and accurate manner is becoming fundamental to many quantum applications. Here, we focus on classical and quantum protocols transferring a state across a double-well potential. The classical protocols are achieved by deforming the potential, while the quantum ones are assisted by a counterdiabatic driving. We show that quantum protocols perform more quickly and accurately. Finally, we design a figure of merit for the performance of the transfer protocols—namely, the protocol grading—that depends only on fundamental physical quantities, and which accounts for the quantum speed limit, the fidelity, and the thermodynamics of the process. We test the protocol grading with classical and quantum protocols, and show that quantum protocols have higher protocol grading than the classical ones.<br/
In Search of Meaning. Ramesses II in his Court of the Luxor Temple
No full textAnalysis of a group of Statues in the ramesside court of Luxor temple. Study of the inscriptions and their meaning in the ideology of Ramesses II
