QUEST FOR THE TIME OPERATOR WITH A SINGLE TRAPPED ION

2011 ◽  
Vol 09 (supp01) ◽  
pp. 189-202 ◽  
Author(s):  
CAROLINE CHAMPENOIS ◽  
THOMAS DURT
Keyword(s):  
Quantum Theory ◽  
Time Operator ◽  
Position Operator ◽  
Experimental Physics ◽  
Trapped Ion ◽  
Quantum Time ◽  
Decay Times ◽  
The Status ◽  
Open Question ◽  
Crucial Experiments

The status of Time in the Quantum Theory remains even today a largely open question. In particular, the existence of a Quantum Time Operator that would describe the distribution of decay times of an unstable quantum system (in analogy with the Position operator that is associated to the position distribution) remained a polemichal question during several decades. Recently, we conceived experimental proposals involving CP violating processes (of single mesons and entangled pairs of mesons) that can be considered as crucial experiments aimed at testing the existence of a Quantum Time Operator. In the present paper, we shall present a similar proposal that can be realized with a single trapped ion. These proposals aim at bringing fundamental problems related to the status of Time in the Quantum Theory to the realm of experimental physics.

scholarly journals CORRELATIONS OF DECAY TIMES OF ENTANGLED COMPOSITE UNSTABLE SYSTEMS

2012 ◽  
Vol 27 (01n03) ◽  
pp. 1345015 ◽  
Author(s):  
THOMAS DURT
Keyword(s):  
Quantum Theory ◽  
Statistical Distribution ◽  
Time Operator ◽  
Unstable Systems ◽  
Unstable Particles ◽  
Decay Times ◽  
The Subject ◽  
Crucial Experiments

The role played by time in the quantum theory is still mysterious by many aspects. In particular it is not clear today whether the distribution of decay times of unstable particles could be described by a time operator (TO). As we shall discuss, different approaches to this problem (one could say interpretations) can be found in the literature on the subject. As we shall show, it is possible to conceive crucial experiments aimed at distinguishing the different approaches, by measuring with accuracy the statistical distribution of decay times of entangled particles. Such experiments can be realized in principle with entangled kaon pairs.

Quantum Becoming?

2017 ◽  
Author(s):  
Craig Callender
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Quantum Time ◽  
Quantum Non Locality ◽  
Time Quantum ◽  
Temporal Becoming ◽  
Non Locality ◽  
Quantum Wavefunction

Two of quantum mechanics’ more famed and spooky features have been invoked in defending the idea that quantum time is congenial to manifest time. Quantum non-locality is said by some to make a preferred foliation of spacetime necessary, and the collapse of the quantum wavefunction is held to vindicate temporal becoming. Although many philosophers and physicists seek relief from relativity’s assault on time in quantum theory, assistance is not so easily found.

scholarly journals Giovanni Aldini: From Animal Electricity to Human Brain Stimulation

2004 ◽  
Vol 31 (4) ◽  
pp. 576-584 ◽  
Author(s):  
André Parent
Keyword(s):  
Electric Current ◽  
Brain Stimulation ◽  
Experimental Physics ◽  
Influential Book ◽  
The University ◽  
Luigi Galvani ◽  
The 19Th Century ◽  
First Time ◽  
Deep Brain ◽  
Crucial Experiments

Two hundred years ago, Giovanni Aldini published a highly influential book that reported experiments in which the principles of Luigi Galvani (animal electricity) and Alessandro Volta (bimetallic electricity) were used together for the first time. Aldini was born in Bologna in 1762 and graduated in physics at the University of his native town in 1782. As nephew and assistant of Galvani, he actively participated in a series of crucial experiments with frog's muscles that led to the idea that electricity was the long-sought vital force coursing from brain to muscles. Aldini became professor of experimental physics at the University of Bologna in 1798. He traveled extensively throughout Europe, spending much time defending the concept of his discreet uncle against the incessant attacks of Volta, who did not believe in animal electricity. Aldini used Volta's bimetallic pile to apply electric current to dismembered bodies of animals and humans; these spectacular galvanic reanimation experiments made a strong and enduring impression on his contemporaries. Aldini also treated patients with personality disorders and reported complete rehabilitation following transcranial administration of electric current. Aldini's work laid the ground for the development of various forms of electrotherapy that were heavily used later in the 19th century. Even today, deep brain stimulation, a procedure currently employed to relieve patients with motor or behavioral disorders, owes much to Aldini and galvanism. In recognition of his merits, Aldini was made a knight of the Iron Crown and a councillor of state at Milan, where he died in 1834.

On the operators for time of motion and delay time induced by scattering

1969 ◽  
Vol 47 (3) ◽  
pp. 279-289 ◽  
Author(s):  
Tran Trong Gien
Keyword(s):  
Quantum Theory ◽  
Explicit Form ◽  
Delay Time ◽  
Scattering Matrix ◽  
Time Operator ◽  
Time Representation ◽  
Scattering Center ◽  
The Mean ◽  
Position Representation ◽  
Mean Time

Recently, Lippmann showed that a time operator might exist in quantum theory and that its explicit form is i ∂/∂E in the energy representation. In this paper, we wish to stress that i ∂/∂E actually represents only the time which the particle used to move from the scattering center to a certain point at the outside. (Later on, we shall call this time the "time of motion.") We also show that, although it is possible to define an operator for the "time of motion" of the particle in the energy representation, it is necessary to introduce a new conjugate representation of the energy representation, the "time representation," to overcome difficulties which may arise in the evaluation of the mean time of motion [Formula: see text]. If the position representation is used for the calculation instead, we shall meet these difficulties. The reason is that time of motion T, position x, and energy E are not two-by-two compatible variables. Bearing in mind that i ∂/∂E only represents the time of motion of the particle, we can then deduce the explicit form of the delay time operator Q in terms of the scattering matrix S directly from the time of motion operator by simple reasoning. This form is Q = −i(∂S/∂E)·S† as was found previously. Some interesting features of the delay time operator will also be sketched at the end of the paper.

scholarly journals Is a time symmetric interpretation of quantum theory possible without retrocausality?

2017 ◽  
Vol 473 (2202) ◽  
pp. 20160607 ◽  
Author(s):  
Matthew S. Leifer ◽  
Matthew F. Pusey
Keyword(s):  
Quantum Theory ◽  
Quantum State ◽  
General Framework ◽  
Bell Inequalities ◽  
Time Symmetry ◽  
Causality Criterion ◽  
The Status ◽  
Interpretation Of Quantum Theory ◽  
Huw Price ◽  
New Interpretation

Huw Price has proposed an argument that suggests a time symmetric ontology for quantum theory must necessarily be retrocausal, i.e. it must involve influences that travel backwards in time. One of Price's assumptions is that the quantum state is a state of reality. However, one of the reasons for exploring retrocausality is that it offers the potential for evading the consequences of no-go theorems, including recent proofs of the reality of the quantum state. Here, we show that this assumption can be replaced by a different assumption, called λ -mediation, that plausibly holds independently of the status of the quantum state. We also reformulate the other assumptions behind the argument to place them in a more general framework and pin down the notion of time symmetry involved more precisely. We show that our assumptions imply a timelike analogue of Bell's local causality criterion and, in doing so, give a new interpretation of timelike violations of Bell inequalities. Namely, they show the impossibility of a (non-retrocausal) time symmetric ontology.

scholarly journals Indistinguishable elements in the origins of quantum statistics. The case of Fermi–Dirac statistics

2022 ◽  
Vol 47 (1) ◽  
Author(s):  
Enric Pérez ◽  
Joana Ibáñez
Keyword(s):  
Quantum Theory ◽  
Critical Analysis ◽  
Seminal Paper ◽  
Stellar Matter ◽  
Quantum Indistinguishability ◽  
Old Quantum Theory ◽  
The Status ◽  
Bose Einstein ◽  
Historical Origins ◽  
Made In

AbstractIn this paper, we deal with the historical origins of Fermi–Dirac statistics, focusing on the contribution by Enrico Fermi of 1926. We argue that this statistics, as opposed to that of Bose–Einstein, has been somewhat overlooked in the usual accounts of the old quantum theory. Our main objective is to offer a critical analysis of Fermi’s seminal paper and its immediate impact. Secondly, we are also interested in assessing the status of the particle concept in the years 1926–1927, especially regarding the germ of quantum indistinguishability. We will see, for example, that the first applications of the Fermi–Dirac statistics to the study of metals or stellar matter had a technical nature, and that their main instigators barely touched upon interpretative matters. Finally, we will discuss the reflections and remarks made in these respects in two famous events in physics of 1927, the Como conference and the fifth Solvay congress.

scholarly journals Uncertainty Relations: Curiosities and Inconsistencies

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1640
Author(s):  
Krzysztof Urbanowski
Keyword(s):  
Quantum Theory ◽  
Lower Bound ◽  
Uncertainty Relation ◽  
Quantum Particle ◽  
Uncertainty Relations ◽  
Rigorous Analysis ◽  
Special Cases ◽  
The Status ◽  
Symmetric Quantum ◽  
Standard Deviations

Analyzing general uncertainty relations one can find that there can exist such pairs of non-commuting observables A and B and such vectors that the lower bound for the product of standard deviations ΔA and ΔB calculated for these vectors is zero: ΔA·ΔB≥0. Here we discuss examples of such cases and some other inconsistencies which can be found performing a rigorous analysis of the uncertainty relations in some special cases. As an illustration of such cases matrices (2×2) and (3×3) and the position–momentum uncertainty relation for a quantum particle in the box are considered. The status of the uncertainty relation in PT–symmetric quantum theory and the problems associated with it are also studied.

Can Quantum Objects Be Tracked?

2018 ◽  
Author(s):  
Otávio Bueno
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Prima Facie ◽  
Constructive Empiricism ◽  
Experimental Physics ◽  
Quantum Particles ◽  
Empirical Level ◽  
Quantum Objects ◽  
Promising Line ◽  
Important Form

Impressively successful at the empirical level and open to multiple interpretations at the theoretical domain, quantum theory provides a rich source of examples of underdetermination. A more promising line of support for realism about quantum mechanics emerges from experimental physics. Some significant experiments have been conducted that prima facie seem to lead to very natural realist readings. The author first considers the challenge these experiments seem to raise to current forms of empiricism, particularly constructive empiricism. Three arguments are examined: the experiments challenge an important form of underdetermination employed by empiricists; the nature of quantum particles, in particular their identity and individuality, seems unproblematic in the context of these experiments, and the experiments provide an unprecedented form of access to the quantum particles involved. The discussion of an empiricist response to these three arguments is shaped by questions regarding the identity, individuality, and individuation of quantum particles in experimental contexts.

scholarly journals TIME IN RELATIVISTIC AND NONRELATIVISTIC QUANTUM MECHANICS

2009 ◽  
Vol 07 (03) ◽  
pp. 595-602 ◽  
Author(s):  
HRVOJE NIKOLIĆ
Keyword(s):  
Quantum Mechanics ◽  
Time Operator ◽  
Position Operator ◽  
Nonrelativistic Quantum ◽  
Time Dynamics ◽  
Bell Theorem ◽  
Time Position ◽  
Nonrelativistic Quantum Mechanics ◽  
Bohmian Interpretation

The kinematic time operator can be naturally defined in relativistic and nonrelativistic quantum mechanics (QM) by treating time on an equal footing with space. The space–time position operator acts in the Hilbert space of functions of space and time. Dynamics, however, makes eigenstates of the time operator unphysical. This poses a problem for the standard interpretation of QM and reinforces the role of alternative interpretations such as the Bohmian one. The Bohmian interpretation, despite of being nonlocal in accordance with the Bell theorem, is shown to be relativistic covariant.

scholarly journals Utp14 interaction with the Small Subunit Processome

2018 ◽  
Author(s):  
Joshua J. Black ◽  
Zhaohui Wang ◽  
Lisa M. Goering ◽  
Arlen W. Johnson
Keyword(s):  
Large Scale ◽  
Ribosomal Subunit ◽  
Small Subunit ◽  
Primary Component ◽  
Uv Crosslinking ◽  
The Status ◽  
Rna Exosome ◽  
Ssu Processome ◽  
Open Question ◽  
Two Hybrid

AbstractThe SSU Processome (sometimes referred to as 90S) is an early stabile intermediate in the small ribosomal subunit biogenesis pathway of eukaryotes. Progression of the SSU Processome to a pre-40S particle requires a large-scale compaction of the RNA and release of many biogenesis factors. The U3 snoRNA is a primary component of the SSU Processome and hybridizes to the rRNA at multiple locations to organize the structure of the SSU Processome. Thus, release of U3 is prerequisite for the transition to pre-40S. Our lab proposed that the RNA helicase Dhr1 plays a crucial role in the transition by unwinding U3 and that this activity is controlled by the SSU Processome protein Utp14. How Utp14 times the activation of Dhr1 is an open question. Despite being highly conserved, Utp14 contains no recognizable domains, and how Utp14 interacts with the SSU Processome is not well characterized. Here, we used UV crosslinking and analysis of cDNA and yeast two-hybrid interaction to characterize how Utp14 interacts with the pre-ribosome. Moreover, proteomic analysis of SSU particles lacking Utp14 revealed that Utp14 is needed for efficient recruitment of the RNA exosome. Our analysis positions Utp14 to be uniquely poised to communicate the status of assembly of the SSU Processome to Dhr1 and possibly the exosome as well.

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