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Maurice de Gosson

Publications and source records attributed to Maurice de Gosson.

At least 55 records · Page 3Linked to original sources
arXiv2016

Born-Jordan Pseudo-Differential Operators with Symbols in the Shubin Classes

We apply Shubin's theory of global symbol classes $Γ_ρ^{m}$ to the Born-Jordan pseudodifferential calculus we have previously developed. This approach has many conceptual advantages, and makes the relationship between the conflicting Born-Jordan and Weyl quantization methods much more limpid. We give, in particular, precise asymptotic expansions of symbols allowing to pass from Born-Jordan quantization to Weyl quantization, and vice-versa. In addition we state and prove some regularity and global hypoellipticity results.

math.FA↗
arXiv2016

Time-frequency Analysis of Born-Jordan Pseudodifferential Operators

Born-Jordan operators are a class of pseudodifferential operators arising as a generalization of the quantization rule for polynomials on the phase space introduced by Born and Jordan in 1925. The weak definition of such operators involves the Born-Jordan distribution, first introduced by Cohen in 1966 as a member of the Cohen class. We perform a time-frequency analysis of the Cohen kernel of the Born -Jordan distribution, using modulation and Wiener amalgam spaces. We then provide sufficient and necessary conditions for Born-Jordan operators to be bounded on modulation spaces. We use modulation spaces as appropriate symbols classes.

math.FA↗
arXiv2016

On the reduction of the interferences in the Born-Jordan distribution

One of the most popular time-frequency representation is certainly the Wigner distribution. To reduce the interferences coming from its quadratic nature, several related distributions have been proposed, among which the so-called Born-Jordan distribution. It is well known that in the Born-Jordan distribution the ghost frequencies are in fact damped quite well, and the noise is in general reduced. However, the horizontal and vertical directions escape from this general smoothing effect, so that the interferences arranged along these directions are in general kept. Whereas these features are graphically evident on examples and heuristically well understood in the engineering community, there is not at present a mathematical explanation of these phenomena, valid for general signals in L^2 and, more in general, in the space S' of temperate distributions. In the present note we provide such a rigorous study using the notion of wave-front set of a distribution. We use techniques from Time-frequency Analysis, such as the modulation and Wiener amalgam spaces, and also results of microlocal regularity of linear partial differential operators.

math.FA↗
arXiv2015

The Phase Space Formulation of Time-Symmetric Quantum Mechanics, I: the Wigner Formalism

Time-symmetric quantum mechanics can be described in the usual Weyl--Wigner--Moyal formalism (WWM) by using the properties of the Wigner distribution, and its generalization, the cross-Wigner distribution. The use of the latter makes clear a strongly oscillating interference between the pre- and post-selected states. This approach allows us to give explicit formulas for the state reconstruction problem, thus generalizing known results to the case of arbitrary observables. In a forthcoming paper we will extend these results to other quantization schemes.

quant-ph↗
arXiv2015

On the Invertibility of Born-Jordan Quantization

As a consequence of the Schwartz kernel Theorem, any linear continuous operator $\widehat{A}:$ $\mathcal{S}(\mathbb{R}^{n})\longrightarrow\mathcal{S}^{\prime}(\mathbb{R}^{n})$ can be written in Weyl form in a unique way, namely it is the Weyl quantization of a unique symbol $a\in\mathcal{S}^{\prime}(\mathbb{R}^{2n})$. Hence, dequantization can always be performed, and in a unique way. Despite the importance of this topic in Quantum Mechanics and Time-frequency Analysis, the same issue for the Born-Jordan quantization seems simply unexplored, except for the case of polynomial symbols, which we also review in detail. In this paper we show that any operator $\widehat{A}$ as above can be written in Born-Jordan form, although the representation is never unique if one allows general temperate distributions as symbols. Then we consider the same problem when the space of temperate distributions is replaced by the space of smooth slowly increasing functions which extend to entire function in $\mathbb{C}^{2n}$, with a growth at most exponential in the imaginary directions. We prove again the validity of such a representation, and we determine a sharp threshold for the exponential growth under which the representation is unique. We employ techniques from the theory of division of distributions.

math.FA↗
arXiv2014

Bohm's Quantum Potential as an Internal Energy

We pursue our discussion of Fermi's surface initiated in Dennis, de Gosson and Hiley and show that Bohm's quantum potential can be viewed as an internal energy of a quantum system. This gives further insight into the role it played by the quantum potential in stationary states. It also allows us to provide a physically motivated derivation of Schrödinger's equation for a particle in an external potential.

quant-ph↗
arXiv2014

On the prolate spheroidal wave functions and Hardy's uncertainty principle

We prove a weak version of Hardy's uncertainty principle using properties of the prolate spheroidal wave functions (PSWFs). We describe the eigenvalues of the sum of a time limiting operator and a band limiting operator acting on L2(R). A weak version of Hardy's uncertainty principle follows from the asymptotic behavior of the largest eigenvalue as the time limit and the band limit approach infinity. An asymptotic formula for this eigenvalue is obtained from its well-known counterpart for the prolate integral operator.

math.FA↗
arXiv2013

Short Time Quantum Propagator and Bohmian Trajectories

We begin by giving correct expressions for the short-time action; following the work of one of us and Makri--Miller. We use these estimates to derive a correct expression modulo modulo delta(t)sqr for the quantum propagator and we show that the quantum potential is negligible modulo delta(t)sqr for a point source. We finally prove that this implies that the quantum motion is classical for very short times.

quant-ph↗
arXiv2012

A pseudo-differential calculus on non-standard symplectic space; spectral and regularity results in modulation spaces

The usual Weyl calculus is intimately associated with the choice of the standard symplectic structure on $\mathbb{R}^{n}\oplus\mathbb{R}^{n}$. In this paper we will show that the replacement of this structure by an arbitrary symplectic structure leads to a pseudo-differential calculus of operators acting on functions or distributions defined, not on $\mathbb{R}^{n}$ but rather on $\mathbb{R}^{n}\oplus\mathbb{R}^{n}$. These operators are intertwined with the standard Weyl pseudo-differential operators using an infinite family of partial isometries of $L^{2}(\mathbb{R}^{n})\longrightarrow L^{2}(\mathbb{R}^{2n})$ \ indexed by $\mathcal{S}(\mathbb{R}^{n})$. This allows us obtain spectral and regularity results for our operators using Shubin's symbol classes and Feichtinger's modulation spaces.

math.FA↗
arXiv2012

Quantum mechanics in phase space: The Schrödinger and the Moyal representations

We present a phase space formulation of quantum mechanics in the Schrödinger representation and derive the associated Weyl pseudo-differential calculus. We prove that the resulting theory is unitarily equivalent to the standard "configuration space" formulation and show that it allows for a uniform treatment of both pure and mixed quantum states. In the second part of the paper we determine the unitary transformation (and its infinitesimal generator) that maps the phase space Schrödinger representation into another (called Moyal) representation, where the wave function is the cross-Wigner function familiar from deformation quantization. Some features of this representation are studied, namely the associated pseudo-differential calculus and the main spectral and dynamical results. Finally, the relation with deformation quantization is discussed.

math-ph↗
arXiv2012

The Reconstruction Problem and Weak Quantum Values

Quantum Mechanical weak values are an interference effect measured by the cross-Wigner transform W(ϕ,ψ) of the post-and preselected states, leading to a complex quasi-distribution ρ_{ϕ,ψ}(x,p) on phase space. We show that the knowledge of ρ_{ϕ,ψ}(z) and of one of the two functions ϕ,ψ unambiguously determines the other, thus generalizing a recent reconstruction result of Lundeen and his collaborators.

math-ph↗
arXiv2011

Zeno Paradox for Bohmian Trajectories: The Unfolding of the Metatron

We analyse the track of an α-particle passing through a cloud chamber using the Bohm theory and show that the resulting classical track has its origins in the quantum Zeno effect. By assuming the ionised gas molecules reveal the positions of the α-particle on its trajectory and using these positions in a short time propagator technique developed by de Gosson, we show it is the failure of the quantum potential to develop quickly enough that leads to the appearance of the classical trajectory. Bohm and Hiley have already argued that it is this failure of the quantum potential to develop appropriately that prevents an Auger electron from undergoing a transition if continuously watched. This allows us to conclude that, in general, it is the suppression of the quantum potential that accounts for the quantum Zeno effect.

quant-ph↗
arXiv2011

Preferred Quantization Rules: Born-Jordan vs. Weyl: the Pseudo-Differential Point of View

There has recently been evidence for replacing the usual Weyl quantization procedure by the older and much less known Born-Jordan rule. In this paper we discuss this quantization procedure in detail and relate it to recent results of Boggiato, De Donno, and Oliaro on the Cohen class. We begin with a discussion of some properties of Shubin's $τ$-pseudo-differential calculus, which allows us to show that the Born-Jordan quantization of a symbol $a$ is the average for $τ\in\lbrack0,1]$ of the $τ$-operators with symbol $a$. We study the properties of the Born-Jordan operators, including their symplectic covariance, and give their Weyl symbol.

math-ph↗
arXiv2010

Construction of Multivariate Gaussian Weyl--Heisenberg Frames, (I)

Let ϕ be an arbitrary generalized Gaussian (squeezed coherent state), Λ_{αβ}=(α_1 Z \times\cdot\cdot\cdot\times α_{n}\mathbb{Z)\times}(β_{1}\mathbb{Z}\times\cdot\cdot\cdot \timesβ_{n}\mathbb{Z)}$ a rectangular lattice. We show that there exists a positive definite symplectic matrix M (depending on ϕ) such that the multivariate Weyl--Heisenberg system G(ϕ,MΛ_{αβ}) is a frame. In a forthcoming Note we will prove a converse to this result.

math-ph↗
arXiv2010

A Characterization of Multivariate Gaussian Weyl--Heisenberg Frames, (II)

In a previous Note we established a necessary and sufficient condition for a multivariate Weyl--Heisenberg system G(ϕ,Λ) to be a frame when the window is a generalized Gaussian (squeezed coherent state) and Λ a rectangular lattice. In this Note we extend this result to lattices of the type $Λ=MZ^{2n}$ where M is a positive definite symmetric matrix.

math-ph↗
arXiv2009

On the Usefulness of Modulation Spaces in Deformation Quantization

We discuss the relevance to deformation quantization of Feichtinger's modulation spaces, especially of the weighted Sjoestrand classes. These function spaces are good classes of symbols of pseudo-differential operators (observables). They have a widespread use in time-frequency analysis and related topics, but are not very well-known in physics. It turns out that they are particularly well adapted to the study of the Moyal star-product and of the star-exponential.

math-ph↗