Conveners
Workshop on continuous variables and quantum information: Session 2
- Natalia Korolkova (University of St. Andrews)
Workshop on continuous variables and quantum information
- Natalia Korolkova (University of St. Andrews)
Workshop on continuous variables and quantum information
- Natalia Korolkova (University of St. Andrews)
Workshop on continuous variables and quantum information
- Ulrik Lund Andersen (Technical University of Denmark)
Workshop on continuous variables and quantum information
- lorenzo maccone
Workshop on continuous variables and quantum information
- Friedrich Koenig (University of St. Andrews)
A nonlinear interferometer, generally, is a sequence of two nonlinear effects occurring coherently. We investigate the properties of such an interferometer consisting of two unseeded high-gain degenerate optical parametric amplifiers (DOPAs). This configuration is known in the literature as an SU(1,1) interferometer and it enables achieving the Heisenberg limit in phase sensitivity. Moreover,...
Ultra-precise measurements of various parameters such as the mass of nano-particles, magnetic fields or gravity can be attained by probing the phononic modes of a micro-mechanical oscillator with light. The sensitivity of such measurements is in part governed by the noise of the phononic mode as well as the noise of the probing light mode, so by decreasing the noise of the probe beam an...
The talk will present an overview of recent theoretical and experimental activities in highly nonlinear quantum optics and optomechanics with continuous variables and a progress in current merging of these two fields. First, we will focus on a generation of instable strong cubic quantum nonlinearities for optical, atomic and optomechanical systems and diagnostics of non-equilibrium and...
Quantum optics allows implementing cryptographic protocols that are verifiably immune against any conceivable attack. Standard telecommunication components allow for an efficient implementation of quantum communication using continuous-variables (CV) of light. At MPL, we routinely implement CV quantum communication based on phase-shift keying of coherent states in combination with homodyne...
In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we make a comparison of the behaviour of continuous variable quantum correlations (quantum entanglement, entropic quantum discord, geometric quantum discord, quantum steering) for a system consisting of: 1) two non-coupled; 2) two coupled bosonic modes embedded in a common environment of...
Einstein-Podolsky-Rosen steerability of quantum states is a property that is different from entanglement and Bell nonlocality. We describe the time evolution of a recently introduced measure that quantifies steerability for arbitrary bipartite Gaussian states in a system consisting of two bosonic modes embedded in a common squeezed thermal environment.
We work in the framework of the theory of...
Entanglement measures proved to be a vital tool for
development of quantum information science. For example, an important
property of entanglement called monogamy is quantitative, and therefore
cannot be captured without introducing entanglement measures.
Additionally, entanglement measures provide useful bounds on several
important hardly computable quantities, and they are indispensable...
As quantum technologies develop the question of verifying/certifying the correctness of the quantum devices is crucial. In particular, as quantum computers will outperform classical, it may be impossible to test the correctness of the quantum computer using a classical. Instead, one need to perform verifiable quantum computation (VBQC). A number of such protocols exist, and we focus on...
Modern cryptography covers much more than encryption of messages in order to keep them secret. Many other cryptographic primitives exist, and it is important to consider how the security of these will be affected in a quantum future. Digital Signatures are a widely used cryptographic primitive, found eg. in e-mail, e-commerce and digital banking, and they form the basis for larger protocols. A...
Continuous Variables are a promising platform for demonstrating large scale quantum information effects thanks to the experimental advantages they provide. In this framework, we define a general quantum computational model based on a continuous variables hardware. It consists in vacuum input states, a finite set of gates — including non-Gaussian elements — and homodyne detection. We show that...
Multimode entanglement is an essential resource for quantum information processing. However, multimode entangled states are generally constructed by targeting a specific entanglement configuration. This yields to a fixed experimental setup that therefore exhibits reduced versatility and scalability. Here we demonstrate a reconfigurable highly multimode entangled state generated by parametric...
Quantum information has traditionally employed qubits (quantum bits) to encode and process quantum information because of their obvious analogy to (classical) bits and the fact that digitisation allows for errors to be corrected, even at the quantum level. Nevertheless, continuous quantum variables afford distinct advantages in terms of producing extremely large-scale resource states...
Relativistic Quantum Information is a novel area of research that aims at understanding the interplay of relativity and quantum physics, using tools from different fields of science, such as Gravity, Quantum Field Theory in Curved Spacetime, Quantum Information, Quantum Metrology and Quantum Thermodynamics.
Research in this area of science has provided novel insight on the role that...
Vacuum fluctuations play a decisive role in many effects in quantum field theory and cosmology. When a parameter in the Lagrangian of the field is modulated by an external pump, vacuum fluctuations stimulate spontaneous downconversion processes, resulting in squeezing between modes symmetric with respect to half of the frequency of the pump. We have observed this phenomenon in the microwave...
A scheme for parallel, high-throughput continuous-variable QKD (CV-QKD) is presented that efficiently utilizes the optical bandwidth resource of broadband squeezed vacuum (of order $10-100$THz), using a novel method for broadband spectrally resolved parametric homodyne measurement. Large multi-bit frames of data can be encoded simultaneously onto the squeezed vacuum spectrum by shaping its...
Shallow water waves scattering on a draining and rotating flow constitute the analogue of a rotating black hole. In such a spacetime, it has been shown theoretically that, at low frequency, waves can extract angular momentum, hence energy from the black hole. Such a process is known as superradiance. In this talk, I will present the experiment conducted at the University of Nottingham that led...
We discuss the question of how many Unruh particles can be found in a finite volume.
There exist various conditions under which waves of positive and negative Klein-Gordon norm can be made to convert into each other.
For example, upon propagating on a curved background, waves of positive and negative norm mix to generate outgoing waves.
As a result of this scattering process, field quanta are spontaneously emitted from the vacuum --- the most famous instance of this effect...
The unitary itself is usually described by an external observer that manipulates an interaction. Including this control into a fully quantum description, a so-called “quantum clock”, is thus a critical step to placing quantum protocols on a firm footing as well as understanding the fundamental limitations of quantum clocks; especially since due to information gain-disturbance principles, it is...
To utilize a scalable quantum network and perform a quantum state transfer within distant arbitrary nodes, the coherence and control of the dynamics of couplings between the information units must be achieved as a prerequisite ingredient for quantum information processing within a hierarchical structure. Graph-theoretic approach provides a powerful tool for the characterization of quantum...
The talk is devoted to discussion of space-time domain finiteness effects for quantum Unruh-DeWitt detector which operates in this domain. We discuss a special
renormalization procedure which happens to be different in finite and infinite domain cases. It is demonstrated that, as is typical for renormalization, a new dimensionfull parameter appears, having meaning of detector's recovery...
