Relativistic quantum field theory imposes additional fundamental restrictions on the distinguishability of quantum states. Because of the unavoidable delocalization of the quantum field states in the Minkowski space-time, the reliable (with unit probability) distinguishability of orthogonal states formally requires infinite time. For the cryptographic protocols which are finite in time the latt...

Algebraic quantum field theory is an approach to relativistic quantum physics, notably the theory of elementary particles, which complements other modern developments in this field. It is particularly powerful for structural analysis but has also proven to be useful in the rigorous treatment of models. In this contribution a non–technical survey is given with emphasis on interesting recent deve...

Orthofermi statistics is characterized by an exclusion principle which is more “exclusive” than Pauli’s exclusion principle: an orbital state shall not contain more than one particle, no matter what the spin direction is. The wavefunction is antisymmetric in spatial indices alone with arbitrary symmetry in the spin indices. Orthobose statistics is corresponding Bose analog: the wavefunction is ...

Quantum field theory is the usual solution to the problems inherent in melding quantum mechanics with special relativity. However, there has also been significant literature on an alternate presentation of relativistic quantum mechanics in terms of an “invariant fifth parameter” in addition to the usual four coordinates of spacetime. When this parameter is treated as parameterizing spacetime pa...

The formulation of relativistic two-body bound state wave equations and their relationship to quantum field theory began with the work by Eddington and Gaunt in 1928 [1]. However, the large variety of approaches attempted in recent years shows that this problem still has no generally agreed-upon solution. Perhaps for this reason, most recent field theory books have skirted this topic. In his re...

In modern quantum information theory one deals with an idealized situation when the spacetime dependence of quantum phenomena is neglected. However the transmission and processing of (quantum) information is a physical process in spacetime. Therefore such basic notions in quantum information theory as qubit, channel, composite systems and entangled states should be formulated in space and time....

The mathematical description of stable particle-like systems appearing in relativistic quantum field theory at large, respectively small scales or non-zero temperatures is discussed.

Up until now, we have dealt with general features of quantum field theories. For example, we have seen how to calculate scattering amplitudes starting from a general Lagrangian. Now we will begin to explore what the Lagrangian of the real world could possibly be. Then, of course, we will discuss what it actually is, or at least what we have figured out about it so far. A good way to start under...