scholarly journals Non-local quantum theory of the scalar field

1967 ◽  
Vol 5 (1) ◽  
pp. 42-56 ◽  
Author(s):  
G. V. Efimov
Keyword(s):  
Quantum Theory ◽  
Scalar Field ◽  
Local Quantum ◽  
Non Local

scholarly journals Non-unitarity of Minkowskian non-local quantum field theories

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Fabio Briscese ◽  
Leonardo Modesto
Keyword(s):  
Scalar Field ◽  
Imaginary Part ◽  
Local Field ◽  
Field Theories ◽  
Unitarity Condition ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Not Given ◽  
Local Quantum ◽  
Non Local

AbstractWe show that Minkowskian non-local quantum field theories are not unitary. We consider a simple one loop diagram for a scalar non-local field and show that the imaginary part of the corresponding complex amplitude is not given by Cutkosky rules, indeed this diagram violates the unitarity condition. We compare this result with the case of an Euclidean non-local scalar field, that has been shown to satisfy the Cutkosky rules, and we clearly identify the reason of the breaking of unitarity of the Minkowskian theory.

scholarly journals Local and Non-Local Invasive Measurements on Two Quantum Spins Coupled via Nanomechanical Oscillations

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1078
Author(s):  
Dimitrios Maroulakos ◽  
Levan Chotorlishvili ◽  
Dominik Schulz ◽  
Jamal Berakdar
Keyword(s):  
Quantum Coherence ◽  
Indirect Measurement ◽  
Quantum Spin ◽  
Quantum States ◽  
Spin Interaction ◽  
First Case ◽  
Composite Quantum System ◽  
Local Quantum ◽  
Non Local ◽  
Quantum Spins

Symmetry plays the central role in the structure of quantum states of bipartite (or many-body) fermionic systems. Typically, symmetry leads to the phenomenon of quantum coherence and correlations (entanglement) inherent to quantum systems only. In the present work, we study the role of symmetry (i.e., quantum correlations) in invasive quantum measurements. We consider the influence of a direct or indirect measurement process on a composite quantum system. We derive explicit analytical expressions for the case of two quantum spins positioned on both sides of the quantum cantilever. The spins are coupled indirectly to each others via their interaction with a magnetic tip deposited on the cantilever. Two types of quantum witnesses can be considered, which quantify the invasiveness of a measurement on the systems’ quantum states: (i) A local quantum witness stands for the consequence on the quantum spin states of a measurement done on the cantilever, meaning we first perform a measurement on the cantilever, and subsequently a measurement on a spin. (ii) The non-local quantum witness signifies the response of one spin if a measurement is done on the other spin. In both cases the disturbance must involve the cantilever. However, in the first case, the spin-cantilever interaction is linear in the coupling constant Ω , where as in the second case, the spin-spin interaction is quadratic in Ω . For both cases, we find and discuss analytical results for the witness.

Manifest non-locality in quantum mechanics, quantum field theory and quantum gravity

2019 ◽  
Vol 34 (28) ◽  
pp. 1941004
Author(s):  
Laurent Freidel ◽  
Robert G. Leigh ◽  
Djordje Minic
Keyword(s):  
Quantum Theory ◽  
String Theory ◽  
Quantum Gravity ◽  
Closed String ◽  
Covariant Formulation ◽  
Quantum Field ◽  
Quantum Geometry ◽  
Local Quantum ◽  
Generic Representation ◽  
Non Locality

We summarize our recent work on the foundational aspects of string theory as a quantum theory of gravity. We emphasize the hidden quantum geometry (modular spacetime) behind the generic representation of quantum theory and then stress that the same geometric structure underlies a manifestly T-duality covariant formulation of string theory, that we call metastring theory. We also discuss an effective non-commutative description of closed strings implied by intrinsic non-commutativity of closed string theory. This fundamental non-commutativity is explicit in the metastring formulation of quantum gravity. Finally we comment on the new concept of metaparticles inherent to such an effective non-commutative description in terms of bi-local quantum fields.

scholarly journals Renormalization and conformal invariance of non-local quantum electrodynamics

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Matthew Heydeman ◽  
Christian B. Jepsen ◽  
Ziming Ji ◽  
Amos Yarom
Keyword(s):  
Conformal Invariance ◽  
Quantum Electrodynamics ◽  
Local Quantum ◽  
Non Local

scholarly journals Gravitational Baryogenesis in Hořava–Lifshitz gravity

2019 ◽  
Vol 34 (25) ◽  
pp. 1950203 ◽  
Author(s):  
Sayani Maity ◽  
Prabir Rudra
Keyword(s):  
Quantum Theory ◽  
Scalar Field ◽  
Chaplygin Gas ◽  
Quantum Corrections ◽  
Theory Of Gravity

In this work, we intend to address the matter–antimatter asymmetry via the gravitational baryogenesis mechanism in the background of a quantum theory of gravity. We investigate this mechanism under the framework of Hořava–Lifshitz gravity. We will compute the baryon-to-entropy ratio in the chosen framework and investigate its physical viability against the observational bounds. We also conduct the above study for various sources of matter like scalar field and Chaplygin gas as specific examples. We speculate that quantum corrections from the background geometry will lead to interesting results.

Sign in / Sign up

Export Citation Format

Share Document