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  • articleNo Access

    New method for merging several exponential operators’ product into one exponential operator

    For two operators X and Y, which obey

    [X,Y]=τY+μ
    we shall prove
    eXeY=exp(X+τY1eτ+μ1eτμτ),
    which means we want to merge two exponential operators’ product into one exponential operator. This kind of operator identity is useful for calculating the quantum entropy S since S=κTr{ρlnρ}, when ρρ1ρ2, but ln(ρ1ρ2)lnρ1+lnρ2, thus the merging operator formula is demanded. In this way, several exponential operators’ product can also be merged. We shall employ the method of integration within normally ordered product (IWOP) to derive the merging operator identity.

  • articleNo Access

    𝒩=2 supersymmetric harmonic oscillator: Basic brackets without canonical conjugate momenta

    We exploit the ideas of spin-statistics theorem, normal-ordering and the key concepts behind the symmetry principles to derive the canonical (anti)commutators for the case of a one (0+1)-dimensional (1D) 𝒩=2 supersymmetric (SUSY) harmonic oscillator (HO) without taking the help of the mathematical definition of canonical conjugate momenta with respect to the bosonic and fermionic variables of this toy model for the Hodge theory (where the continuous and discrete symmetries of the theory provide the physical realizations of the de Rham cohomological operators of differential geometry). In our present endeavor, it is the full set of continuous symmetries and their corresponding generators that lead to the derivation of basic (anti)commutators amongst the creation and annihilation operators that appear in the normal mode expansions of the dynamical fermionic and bosonic variables of our present 𝒩=2 SUSY theory of a HO. These basic brackets are in complete agreement with such kind of brackets that are derived from the standard canonical method of quantization scheme.

  • chapterNo Access

    TWO NORMAL ORDERING PROBLEMS AND CERTAIN SHEFFER POLYNOMIALS

    The first normal ordering problem involves bosonic harmonic oscillator creation and annihilation operators (Heisenberg algebra). It is related to the problem of finding the finite transformation generated by Lk−1 := −zkz, k ∈ ℤ, z ∈ ℂ (conformal algebra generators). It can be formulated in terms of a subclass of Sheffer polynomials called Jabotinsky polynomials. The coefficients of these polynomials furnish generalized Stirling number triangles of the second kind, called S2(k;n,m) for k ∈ ℤ. Generalized Stirling-numbers of the first kind, S1(k;n, m) are also defined.

    The second normal ordering problem appears in thermo-field dynamics for the harmonic Bose oscillator. Again Sheffer polynomials appear. They relate to Euler numbers and iterated sums of squares. In a different approach to this problem one solves the differential-difference equation fn+1 = f'n + n2 fn-1, n > = 1, with certain inputs f0 and f1 = f'0.

    In this case the integer coefficients of the special Sheffer polynomials which emerge have an interpretation as sum over multinomials for some subset of partitions.