The conceptual and the anecdotal history of quantum mechanics

The aim of this paper is to combine the intellectual and the psychosocial aspects. blurring the distinction between the conceptual and the anecdotal history of quantum mechanics. The full realization of the importance of such anecdotal factors leads to the revision of our understanding of the conceptual development itself. The paper concludes with the suggestion that a major part of numerous inconsistencies in the Copenhagen interpretation of quantum physics are of a psychosocial origin.     

A quantum network for implementation of the optimal quantum cloning

This paper presents a quantum network to implement the optimal 1→2 quantum cloning in 2 dimensions, including the optimal asymmetric universal, the optimal symmetric phase-covariant, and the asymmetric real state cloning. By only choosing different angles of the single-qubit rotations, the quantum network can implement three optimal quantum cloning.     

A family of quantum protocols

We introduce three new quantum protocols involving noisy quantum channels and entangled states, and relate them operationally and conceptually with four well-known old protocols. Two of the new protocols (the mother and father) can generate the other five "child" protocols by direct application of teleportation and superdense coding, and can be derived in turn by making the old protocols "coherent." This gives very simple proofs for two famous old protocols (the hashing inequality and quantum channel capacity) and provides the basis for optimal trade-off curves in several quantum information processing tasks.     

A one-way quantum computer

We present a scheme of quantum computation that consists entirely of one-qubit measurements on a particular class of entangled states, the cluster states. The measurements are used to imprint a quantum logic circuit on the state, thereby destroying its entanglement at the same time. Cluster states are thus one-way quantum computers and the measurements form the program.     

A quantum computer on the basis of an atomic quantum transistor with built-in quantum memory

A quantum transistor based quantum computer where the multiqubit quantum memory is a component of the quantum transistor and, correspondingly, takes part in the performance of quantum logical operations is considered. Proceeding from the generalized Jaynes–Cummings model, equations for coefficients of the wave function of the quantum system under consideration have been obtained for different stages of its evolution in processes of performing logical operations. The solution of the system of equations allows one to establish requirements that are imposed on the parameters of the initial Hamiltonian and must be satisfied for the effective operation of the computer; it also demonstrates the possibility of a universal set of quantum operations. Thus, based on the proposed approach, the possibility of constructing a compact multiatomic ensemble based on quantum computer using a quantum transistor for the implementation of two-qubit gates has been demonstrated.     

A quiver quantum group

We construct quantum groups at a root of unity and we describe their monoidal module category using techniques from the representation theory of finite dimensional associative algebras.Supported by the FNSRS (Swiss National Foundation)     

A transient quantum effect

A transient quantum effect is shown to occur for a superposition of stationary states. An alternative to Schrödinger's equation is considered which predicts a transient effect even for energy eigenstates.     

A quaternion quantum system

The (generalized) quantum mechanics of the two-dimensional quaternionic Hilbert space is constructed explicitly. In this simple example the unconventional properties of such a system as compared to complex quantum mechanics are discussed.     

A brief history of measurement

The aim of this paper is to situate the subject of measurement and metrology in its historical and philosophical context. Everyone agrees that the numeration of objects and the quantification of the characteristics of some simple systems are very ancient practices encountered in any specific civilisation. Indeed the link between measurement and numeration comes from the beginnings. This is recalled here, as are the links between units and money, between references and authority. Then, the paper identifies and exhibits the different epistemological gaps occurred – or occurring – in the history of measurement in the western countries: geometry versus arithmetics, model versus experiment, prediction versus uncertainty, determinism versus quantum physics. Those gaps are described in relationship to the evolution of the internationally agreed system of units.     

A brief history of PEEM

The evolution of cathode lens-based photo emission electron microscopy (PEEM) from the simple beginnings in the early 1930s to its sophisticated present state is discussed. In addition to conventional ultraviolet light-excited PEEM (UV-PEEM), laser excited PEEM and the various modes of synchrotron X-ray-excited PEEM (XPEEM) particular emphasis is placed on the complementary combination of these methods with low energy electron microscopy (LEEM).     

A novel quantum block encryption algorithm based on quantum computation

Based on quantum computation, a novel quantum block cryptographic algorithm that can be used to encrypt classical messages is proposed. The security of this algorithm is analyzed from several aspects. It is shown that the quantum block cryptographic algorithm, in which the key can be reused after undergoing a check procedure, can prevent quantum attack strategy as well as classical attack strategy. The problem of key management is discussed and the circuits for encryption and decryption are suggested.     

A concise review of Rydberg atom based quantum computation and quantum simulation

Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago.Recent experimental and theoretical progresses have shined exciting light on this avenue.In this concise review,we will briefly introduce the basics of Rydberg atoms and their recent applications in associated areas of neutral atom quantum computation and simulation.We shall also include related discussions on quantum optics with Rydberg atomic ensembles,which are increasingly used to explore quantum computation and quantum simulation with photons.     

A classification of quantum Hall fluids

In this paper, the key ideas of characterizing universality classes of dissipationfree (incompressible) quantum Hall fluids by mathematical objects called quantum Hall lattices are reviewed. Many general theorems about the classification of quantum Hall lattices are stated and their physical implications are discussed. Physically relevant subclasses of quantum Hall lattices are defined and completely classified. The results are carefully compared with experimental data and also with other theoretical schemes (the hierarchy schemes). Several proposals for new experiments are made which could help to settle interesting issues in the theory of the (fractional) quantum Hall effect and thus would lead to a deeper understanding of this remarkable effect.     

A cinematic study of quantum kinematics

Within the framework of stochastic quantization, quantum mechanical trajectory of a particle is computed numerically. The fundamental kinematic equation is a stochastic differential equation which can be intergrated numerically by means of pseudo random numbers. Three typical examples in quantum mechanics, the superposition, the classical limit, and the two-slit interference, are considered in detail. The computer output of the numerical analysis of these examples is shown in a grapic display. Several samples of the quantum mechanical trajectories are illustrated there from which intuitive meaning of quantum phenomena appearing in the examples can be seen easily.     

A classical realization of quantum mechanics

A mechanism is presented by which a classical system could be described by the laws of quantum theory. Conflict with von Neumann's no-go theorem is avoided. Experimental predictions are made.     

A quantum trajectory description of decoherence

A complete theoretical treatment in many problems relevant to physics, chemistry, and biology requires considering the action of the environment over the system of interest. Usually the environment involves a relatively large number of degrees of freedom, this making the problem numerically intractable from a purely quantum-mechanical point of view. To overcome this drawback, a new class of quantum trajectories is proposed. These trajectories, based on the same grounds as Bohmian ones, are solely associated to the system reduced density matrix, since the evolution of the environment degrees of freedom is not considered explicitly. Within this approach, environment effects come into play through a time-dependent damping factor that appears in the system equations of motion. Apart from their evident computational advantage, this type of trajectories also results very insightful to understand the system decoherence. In particular, here we show the usefulness of these trajectories analyzing decoherence effects in interference phenomena, taking as a working model the well-known double-slit experiment.