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Yatendra S. Jain

Publications and source records attributed to Yatendra S. Jain.

17 recordsLinked to original sources
arXiv2012

On the free rotation of a molecule embedded in helium-4 clusters

The fact, that $^4$He atoms on different concentric circular paths around the axis of a quantum vortex move with identically equal angular momentum, which represents an important aspect of superfluidity of He-II, has been used to discover a model which can explain the {\it typical nature} of experimentally observed $N$ (number of $^4He$ atoms) dependence of the rotational constant ($B$) of the rotor part of a cluster M:He$_N$. It reveals how exactly superfluidity is related to the said dependence of $B$ on $N$. We believe that this model, when used with simulation techniques, would render results that would agree closely with experiments.

cond-mat.other↗
arXiv2011

Quantum dynamics of OCS molecule doped in superfluid 4He nanodroplet

In this paper, we explain the change of rotational constant (B) and vibrational frequency shift of 4HeN-OCS clusters with N by using important inferences of Macro-Orbital theory of superfluidity and several other factors that can change B and vibrational frequency. Consequently, this helps us in understanding the extra ordinary experimental observations that (i) B decreases monotonically from N = 1 to 9 and rises thereafter to follow broad oscillations with maxima at N = 24, 47 and minima at 36 and 62 and (ii) vibrational frequency shift has blue shift for N ~ 1 - 6, with steady red shift thereafter having a change in slope at N ~ 17.

cond-mat.other↗
arXiv2011

On the origin of Stark effect of rotons in He-II and the existence of p = 0 condensate

Linear Stark effect of roton transition, experimentally observed through microwave absorption in He-II (superfluid He) in the presence of varying external electric field, is critically analysed. We find that: (i) The effect cannot be explained in terms of conventional microscopic theory (CMT) of He-II which presumes the existence of p = 0 condensate and concludes that He atoms even at T = 0 have random motions and mutual collisions which do not support the basic factor (viz. an ordered arrangement of atomic electric dipoles) needed for its occurrence. (ii) The desired order is concluded, rather, by a non-conventional microscopic theory (NCMT) as an intrinsic property of He-II. Accordingly, all atoms in He-II define a closepacked arrangement of their wave packets (CPA-WP) with identically equal nearest neighbour distance (d), per particle zero-point energy (ε0 = h2/8md2) and equivalent momentum, h/2d. (iii) The CPA-WP prevent atoms from having relative motions and mutual collisions capable of disturbing any order of atomic dipoles. As such the NCMT and the observed Stark effect have strong mutual support; whereas the former concludes CPA-WP necessary for the occurrence of the effect, the latter strengthens the experimental support for the former, which means that theobservation does not support the presence of p = 0 condensate in He-II.

cond-mat.other↗
arXiv2011

Quantum dynamics of molecules in 4He nano-droplets: Microscopic Superfluidity

High resolution spectroscopy of doped molecules in 4He nano-droplets and clusters gives a signature of superfluidity in microscopic system, termed as microscopic superfluidity. Ro-vibrational spectrum of 4HeN-M clusters is studied with the help of some important observations, revealed from experiments (viz., localised and orderly arrangement of 4He atoms, although, being free to move in the order of their locations; individual 4He atoms can not be tagged as normal/ superfluid, etc.) and other factors (e.g., consideration that the 4He atoms which happen to fall in the plane of rotation of a molecule, render a equipotential ring and thus, do not take part in rotation; etc.) which effect the rotational and vibrational spectrum of the system. This helps us in successfully explaining the experimental findings which state that the rotational spectrum of clusters have sharp peaks (indicating that the molecule rotates like a free rotor) and moment of inertia and vibrational frequency shift have a non-trivial dependence on N.

cond-mat.other↗
arXiv2011

Ro-vibrational dynamics of N2O in superfluid 4He nano-droplets

In this paper we use the important interferences of Macro-Orbital theory of superfluidity clubbed with several factors that can change the rotational constant (B) and vibrational frequency of N2O in 4HeN-N2O clusters with N to account for the results of their recently reported spectroscopic studies which conclude that: (i) in spite of the fact that 4He atoms provide an interactive medium, the rotational spectrum of the clusters shows sharp peaks, similar to that of the molecule in gaseous state, indicating that the molecule rotates like a free rotor, (ii) B decreases monotonically from N = 1 to 6, remains nearly constant for N = 6 to 8 and increases for N = 9 to 10 with small oscillations there after and (iii) vibrational frequency exhibits blue shift for N = 1 to 5 and a red shift for higher N.

cond-mat.other↗
arXiv2010

Experimental realities refuting the existence of p=0 condensate in a system of interacting bosons : II. Spectroscopy of embedded molecules

Experimental observation of superfluidity in a microscopic cluster, $M:(^4He)_x$, of a molecule ($M$) and $x$ number of $^4He$ atoms (with $x$ ranging from 1 to many) is qualitatively analyzed. It concludes that: (i) each $^4He$ atom in the cluster has to have non-zero momentum for its confinement to a space of size ($<$ the size of the cluster), (ii) superfluidity does not require atoms with zero momentum ($p=0$), and (iii) while all $^4He$ atoms in the cluster cease to have relative motions (hence the inter-atomic collisions), they retain a freedom to move coherently in order of their locations on a closed path around the rotor ($M$ plus few nearest $^4He$ atoms which follow the molecular rotation for their relatively strong binding with $M$). The analysis also identifies the basic arrangement of $^4He$ atoms which allows the rotor to have free rotation in the cluster.

cond-mat.other↗
arXiv2010

Experimental realities refuting existence of p=0 condensate in a system of interacting bosons : I. Electron bubble

Physical reality of the existence of electron bubble in liquid $^4He$ (or $^3He$) renders a {\it clear experimental evidence} for a quantum particle (in an interacting environment as seen by electron in liquid helium) to occupy exclusively a space of size $λ/2$ that, obviously, depends on its energy/momentum. This unequivocally proves that {\it no particle} in a system of interacting bosons such as liquid $^4He$ has momentum $p=0$; in stead, {\it all particles} in the ground state of such a system are in the single quantum state of energy $\varepsilon_o = h^2/8md^2$ or momentum $p = h/2d$.

cond-mat.other↗
arXiv2010

The p=0 condensate is a myth

Analyzing some of the basic aspects of the dynamics of two bosons (interacting through a central force) and their importance in determining the ground state of a system like liquid $^4He$, it is unequivocally concluded that our conventional belief in the existence $p=0$ condensate in the superfluid state of such systems [including the state of Bose Einstein condensate (BEC) of trapped dilute gases] is a myth.

cond-mat.quant-gas↗
arXiv2009

Physical behavior of a system representing a particle trapped in a box having flexible size

A critical study of the wave mechanics of a particle trapped in a 1-D box having infinite potential walls and small flexibility in its size reveals its several important and hither to unknown aspects which could be relevant for better understanding of systems like quantum -dot/wire/well. Since most of these aspects arise from the zero-point force coming into operation when the particle occupies its ground state in the box, they are expected to have great significance at low temperatures. To demonstrate this we briefly analyze some important aspects of an electron bubble in liquid helium and its nano-droplets.

cond-mat.mtrl-sci↗
arXiv2006

Logarithmic Singularities of Specific Heat and Related Properties of Liquid $^4He$ Near $λ-$Point

The singularity of specific heat ($C_p$) and related properties (viz. thermal expansion coefficient, compressibility and pressure coefficient) of liquid $^4He$ at $λ-$point is studied and the accuracy of its logarithmic nature as concluded for the first time from a microscopic theory (cond-mat/0606571) of a system of interacting bosons is examined. A very good agreement between the results of this theory and experiments concludes that singularity is intrinsically logarithmic. However, as shown by other studies, weak effects arising from earth's gravity and small sample size round it off and $C_p$ assumes asymptotic nature near $T_λ$.

cond-mat.stat-mech↗
arXiv2006

Superfluid $T_c$ of Helium-3 and its Pressure Dependence

Superfluid $T_c$ of liquid helium-3 and its pressure dependence are calculated by using a relation obtained from our macro-orbital microscopic theory. The results agree closely with experiments. This underlines the accuracy of our relation and its potential to provide superfluid $T_c$ of electron fluid in widely different superconductors and renders experimental foundation to our conclusion related to the basic factors responsible for the formation of (q, -q) bound pairs of fermions and the onset of superfluidity in a fermionic system.

cond-mat.supr-con↗
arXiv2006

A Study of Elementary Excitations of Liquid Helium-4 Using Macro-orbital Microscopic Theory

Energy of elementary excitations and the anomalous nature of small Q phonons in He-II are studied by using our macro-orbital microscopic theory of a system of interacting bosons (cond-mat/0606571). It is observed that : (i) the experimental E(Q) of He-II not only agrees with our theoretical relation $E(Q) = \hbar^2Q^2/4mS(Q)$ but also supports an important conclusion of Price that S(0) should have zero value for quantum fluids, and (ii) Feynman's energy of excitations $E(Q)_{Fyn} = \hbar^2Q^2/2mS(Q)$ equals approximately to $2E(Q)_{exp}$ even at low Q. Three problems with the Feynman's inference that $E(Q)_{Fyn}$ has good agreement with $E(Q)_{exp}$ at low Q are identified. It is argued that the theory can also be used to understand similar spectrum of the BEC state of a dilute gas reported by O'Dell et al.

cond-mat.soft↗
arXiv2006

Macro-orbitals and microscopic theory of a system of interacting bosons

Macro-orbital representation of a particle (detailed account given in cond-mat/0603784) has been used to develop the microscopic theory of a system of interacting bosons. It concludes that: (i) below certain temperature (say, $T_λ$), particles assume a state of (q, -q) bound pairs, (ii) the $λ-$transition is a consequence of inter-particle quantum correlations clubbed with zero-point repulsion and inter-particle attraction and represents an onset of the order-disorder of particles in their $ϕ-$space followed simultaneously by their BEC as (q, -q) bound pairs in a state of q = $q_o = π/d$ and K = 0, (iii) particles at $T \le T_λ$ acquire collective binding which locks them at = 0, = $λ/2$ and $Δϕ= 2nπ$ (with n = 1, 2, 3, ...), (iv) the entire system assumes mechanical strain in inter-particle bonds and behaves like a single macroscopic molecule, (v) there exists an energy gap between the superfluid and normal fluid phases of the system, (vi) the $λ-$transition represents the twin phenomena of broken gauge symmetry and phase coherence, (vii) the system does not have p = 0 condensate, (viii) a new kind of quantum quasi-particle "omon" (a phononlike wave of the oscillations of the momentum coordinates of particles) exists in superfluid phase, etc. It explains the properties of He-II, including the origin of quantized vortices, critical velocities, logarithmic singularity of specific heat, etc. at quantitative level and provides microscopic foundation to two fluid theory, $Ψ-$theory, idea of macroscopic wave function, etc. The framework of the theory can unify the physics of interacting bosons and fermions.

cond-mat.soft↗
arXiv2006

Untouched aspects of the wave mechanics of a particle in one dimensional box

Wave mechanics of a particle in 1-D box (size $= d$) is critically analyzed to reveal its untouched aspects. When the particle rests in its ground state, its zero-point force ($F_o$) produces non-zero strain by modifying the box size from $d$ to $d' = d + Δd$ in all practical situations where the force ($F_a$) restoring $d$ is not infinitely strong. Assuming that $F_a$ originates from a potential $\propto x^2$ ($x$ being a small change in $d$), we find that: (i) the particle and strained box assume a mutually bound state (under the equilibrium between $F_o$ and $F_a$) with binding energy $Δ{E} = -ε_o'Δ{d}/d'$ (with $ε_o' = h^2/8md'^2$ being the ground state energy of the particle in the strained box), (ii) the box size oscillates around $d'$ when the said equilibrium is disturbed, (iii) an exchange of energy between the particle and the strained box occurs during such oscillations, and (iv) the particle, having collisional motion in its excited states, assumes collisionless motion in its ground state. These aspects have desired experimental support and proven relevance for understanding the physics of widely different systems such as quantum dots, quantum wires, trapped single particle/ion, clusters of particles, superconductors, superfluids, {\it etc.} It is emphasized that the physics of such a system in its low energy states can be truly revealed if the theory incorporates $F_o$ and related aspects.

quant-ph↗
arXiv2006

Basic Foundations of the Microscopic Theory of Superconductivity

A new approach based on macro-orbital representation of a conduction electron in a solid has been used to discover some untouched aspects of the phonon induced attraction between two electrons and to lay the basic foundations of a general theory of superconductivity applicable to widely different solids. To this effect we first analyze the net hamiltonian, H(N), of N conduction electrons to identify its universal part, H_o(N) (independent of the nature of a specific solid or a specific class of solids), and then study the states of H_o(N) to conclude that superconductivity originates, basically, from an inter-play between the zero- point force (f_o) of conduction electrons in their ground state and the inter-atomic forces (f_a) which decide the lattice structure. This renders a kind of mechanical strain in the lattice which serves as the main source of phonon induced inter-electron attraction responsible for the formation of Cooper type pairs and the onset of superconductivity below certain temperature T_c. We determine the binding energy of such pairs and find a relation for T_c which not only accounts for the highest experimental T_c = 135 K that we know to-day but also indicates that superconductivity may, in principle, occur at room temperature. It is evident that electrical strain in the lattice (i.e., electrical polarization of the lattice constituents produced by the charge of conducting electrons) can have an added contribution to the phonon induced attraction of two electrons. Our theoretical framework not only incorporates BCS model but also provides microscopic basis for the two well known phenomenologies of superconductivity, viz., the two fluid theory and Psi-theory. In addition, it also corroborates a recent idea that superconducting transition is basically a quantum phase transition.

cond-mat.supr-con↗
arXiv2006

Wave Mechanics of Two Hard Core Quantum Particles in 1-D Box

The wave mechanics of two impenetrable hard core particles in 1-D box is analyzed. Each particle in the box behaves like an independent entity represented by a {\it macro-orbital} (a kind of pair waveform). While the expectation value of their interaction, $ $, vanishes for every state of two particles, the expectation value of their relative separation, $ $, satisfies $ \ge λ/2$ (or $q \ge π/d$, with $2d = L$ being the size of the box). The particles in their ground state define a close-packed arrangement of their wave packets (with $ = λ/2$, phase position separation $Δϕ= 2π$ and momentum $|q_o| = π/d$) and experience a mutual repulsive force ({\it zero point repulsion}) $f_o = h^2/2md^3$ which also tries to expand the box. While the relative dynamics of two particles in their excited states represents usual collisional motion, the same in their ground state becomes collisionless. These results have great significance in determining the correct microscopic understanding of widely different many body systems.

quant-ph↗