scholarly journals How Does the Planck Scale Affect Qubits?

2021 ◽  
Vol 3 (1) ◽  
pp. 196-227
Author(s):  
Matthew J. Lake
Keyword(s):  
Planck Scale ◽  
Direct Result ◽  
Uncertainty Relations ◽  
Spin States ◽  
Spin Part ◽  
Composite State ◽  
Interaction Terms ◽  
Small Correction ◽  
Spin Sector ◽  
Degenerate Eigenvalues

Gedanken experiments in quantum gravity motivate generalised uncertainty relations (GURs) implying deviations from the standard quantum statistics close to the Planck scale. These deviations have been extensively investigated for the non-spin part of the wave function, but existing models tacitly assume that spin states remain unaffected by the quantisation of the background in which the quantum matter propagates. Here, we explore a new model of nonlocal geometry in which the Planck-scale smearing of classical points generates GURs for angular momentum. These, in turn, imply an analogous generalisation of the spin uncertainty relations. The new relations correspond to a novel representation of SU(2) that acts nontrivially on both subspaces of the composite state describing matter-geometry interactions. For single particles, each spin matrix has four independent eigenvectors, corresponding to two 2-fold degenerate eigenvalues ±(ℏ+β)/2, where β is a small correction to the effective Planck’s constant. These represent the spin states of a quantum particle immersed in a quantum background geometry and the correction by β emerges as a direct result of the interaction terms. In addition to the canonical qubits states, |0⟩=|↑⟩ and |1⟩=|↓⟩, there exist two new eigenstates in which the spin of the particle becomes entangled with the spin sector of the fluctuating spacetime. We explore ways to empirically distinguish the resulting "geometric" qubits, |0′⟩ and |1′⟩, from their canonical counterparts.

scholarly journals On deformations of classical mechanics due to Planck-scale physics

2020 ◽  
Vol 29 (10) ◽  
pp. 2050070
Author(s):  
Olga I. Chashchina ◽  
Abhijit Sen ◽  
Zurab K. Silagadze
Keyword(s):  
Quantum System ◽  
Evolution Equations ◽  
Hidden Variables ◽  
Classical Mechanics ◽  
Planck Scale ◽  
Leibniz Rule ◽  
Uncertainty Relations ◽  
Interesting Possibility ◽  
Heisenberg Uncertainty ◽  
Space Formulation

Several quantum gravity and string theory thought experiments indicate that the Heisenberg uncertainty relations get modified at the Planck scale so that a minimal length do arises. This modification may imply a modification of the canonical commutation relations and hence quantum mechanics at the Planck scale. The corresponding modification of classical mechanics is usually considered by replacing modified quantum commutators by Poisson brackets suitably modified in such a way that they retain their main properties (antisymmetry, linearity, Leibniz rule and Jacobi identity). We indicate that there exists an alternative interesting possibility. Koopman–von Neumann’s Hilbert space formulation of classical mechanics allows, as Sudarshan remarked, to consider the classical mechanics as a hidden variable quantum system. Then, the Planck scale modification of this quantum system naturally induces the corresponding modification of dynamics in the classical substrate. Interestingly, it seems this induced modification in fact destroys the classicality: classical position and momentum operators cease to be commuting and hidden variables do appear in their evolution equations.

scholarly journals Experimental Test of Residual Error-Disturbance Uncertainty Relations for Mixed Spin-½States

2016 ◽  
Vol 117 (14) ◽  
Author(s):  
Bülent Demirel ◽  
Stephan Sponar ◽  
Georg Sulyok ◽  
Masanao Ozawa ◽  
Yuji Hasegawa
Keyword(s):  
Experimental Test ◽  
Residual Error ◽  
Uncertainty Relations ◽  
Spin States ◽  
Mixed Spin

scholarly journals DEFORMED DENSITY MATRIX AND GENERALIZED UNCERTAINTY RELATION IN THERMODYNAMICS

2004 ◽  
Vol 19 (01) ◽  
pp. 71-81 ◽  
Author(s):  
A. E. SHALYT-MARGOLIN ◽  
A. YA. TREGUBOVICH
Keyword(s):  
Statistical Mechanics ◽  
Density Matrix ◽  
Uncertainty Relation ◽  
Planck Scale ◽  
Additional Term ◽  
Temperature Limit ◽  
Quantum Mechanical ◽  
Uncertainty Relations ◽  
Primary Object ◽  
Complete Analogy

A generalization of the thermodynamic uncertainty relations is proposed. It is done by introducing an additional term proportional to the interior energy into the standard thermodynamic uncertainty relation that leads to existence of the lower limit of inverse temperature. In our opinion the approach proposed may lead to the proofs of these relations. To this end, the statistical mechanics deformation at Planck scale. The statistical mechanics deformation is constructed by analogy to the earlier quantum mechanical results. As previously, the primary object is a density matrix, but now the statistical one. The obtained deformed object is referred to as a statistical density pro-matrix. This object is explicitly described, and it is demonstrated that there is a complete analogy in the construction and properties of quantum mechanics and statistical density matrices at Planck scale (i.e. density pro-matrices). It is shown that an ordinary statistical density matrix occurs in the low-temperature limit at temperatures much lower than the Planck's. The associated deformation of a canonical Gibbs distribution is given explicitly.

An interactions-based interpretation for quantum mechanics

2020 ◽  
Vol 33 (1) ◽  
pp. 1-9
Author(s):  
J. M. Kerr
Keyword(s):  
Wave Function ◽  
Quantum Mechanics ◽  
Small Group ◽  
Planck Scale ◽  
Direct Result ◽  
Conceptual Basis ◽  
State Reduction ◽  
Background Theory ◽  
Collapse Theories ◽  
Epistemic Aspect

A small group of simple, lateral assumptions about the structure and nature of space, some of them at the Planck scale, produces a new conceptual basis. The background theory allows a rederivation of several areas of theory it interprets, leading in other areas to alternative mathematics that closely mimics existing physics, but diverging enough for testable predictions. This paper focusses on the phenomenology of quantum mechanics (QM), with a nonlocal interpretation, in which the wave function is primarily ontic, but also has an epistemic aspect. It differs widely from all other interpretations for QM, but has general similarities to some objective collapse theories, and in particular to relational QM (RQM). State reduction is set off by interactions, not measurements, but unlike in RQM, the “exchange of information” between two systems is not only made possible by the interaction, it is a direct result of it. The interpretation includes an explanation for quantization, the probabilistic aspect of QM, entanglement, and state reduction as in decoherence.

scholarly journals The Weak Gravity Conjecture and axion strings

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Ben Heidenreich ◽  
Matthew Reece ◽  
Tom Rudelius
Keyword(s):  
Gauge Theory ◽  
High Spin ◽  
Planck Scale ◽  
Mass Scale ◽  
Spin States ◽  
High Spin States ◽  
Weakly Coupled ◽  
Klein Theory ◽  
Weak Gravity ◽  
Kaluza Klein

Abstract Strong (sublattice or tower) formulations of the Weak Gravity Conjecture (WGC) imply that, if a weakly coupled gauge theory exists, a tower of charged particles drives the theory to strong coupling at an ultraviolet scale well below the Planck scale. This tower can consist of low-spin states, as in Kaluza-Klein theory, or high-spin states, as with weakly-coupled strings. We provide a suggestive bottom-up argument based on the mild p-form WGC that, for any gauge theory coupled to a fundamental axion through a θF ∧ F term, the tower is a stringy one. The charge-carrying string states at or below the WGC scale gMPl are simply axion strings for θ, with charged modes arising from anomaly inflow. Kaluza-Klein theories evade this conclusion and postpone the appearance of high-spin states to higher energies because they lack a θF ∧ F term. For abelian Kaluza-Klein theories, modified arguments based on additional abelian groups that interact with the Kaluza-Klein gauge group sometimes pinpoint a mass scale for charged strings. These arguments reinforce the Emergent String and Distant Axionic String Conjectures. We emphasize the unproven assumptions and weak points of the arguments, which provide interesting targets for further work. In particular, a sharp characterization of when gauge fields admit θF ∧ F couplings and when they do not would be immensely useful for particle phenomenology and for clarifying the implications of the Weak Gravity Conjecture.

scholarly journals Closed strings and weak gravity from higher-spin causality

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Jared Kaplan ◽  
Sandipan Kundu
Keyword(s):  
Planck Scale ◽  
Closed String ◽  
Spin States ◽  
Quantum Field ◽  
Spin Particle ◽  
Regge Trajectories ◽  
Gravity Condition ◽  
Weakly Coupled ◽  
Higher Spin ◽  
Weak Gravity

Abstract We combine old and new quantum field theoretic arguments to show that any theory of stable or metastable higher spin particles can be coupled to gravity only when the gravity sector has a stringy structure. Metastable higher spin particles, free or interacting, cannot couple to gravity while preserving causality unless there exist higher spin states in the gravitational sector much below the Planck scale Mpl. We obtain an upper bound on the mass Λgr of the lightest higher spin particle in the gravity sector in terms of quantities in the non-gravitational sector. We invoke the CKSZ uniqueness theorem to argue that any weakly coupled UV completion of such a theory must have a gravity sector containing infinite towers of asymptotically parallel, equispaced, and linear Regge trajectories. Consequently, gravitational four-point scattering amplitudes must coincide with the closed string four-point amplitude for s, t ≫ 1, identifying Λgr as the string scale. Our bound also implies that all metastable higher spin particles in 4d with masses m ≪ Λgr must satisfy a weak gravity condition.

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

DESCRIPTION OF HIGH SPIN STATES

1980 ◽  
Vol 41 (C10) ◽  
pp. C10-143-C10-154 ◽  
Author(s):  
A. Faessler
Keyword(s):  
High Spin ◽  
Spin States ◽  
High Spin States
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