Trace Definition and 190 Threads

Homework Statement I want to show that tr\left(\hat{\rho}_{mixed}\right)=1 tr\left(\hat{\rho}_{mixed}^{2}\right)<1 when \hat{\rho}_{mixed}=\frac{1}{2\pi}\int_{0}^{2\pi}d \alpha \hat{\rho}(\psi) Homework Equations tr\left(\psi\right)= \sum_{n}\langle n|\psi|n\rangle...

Hi everyone. I'm not sure this is the correct section for this topic and if not my apologiez. I'm studying SU(3) and my professor wrote down the following equality: $$Tr\left(\left[ T^a_8,T^b_8\right] T^c_8\right)=i\frac{3}{2}f^{abc}$$ where Ts are generators of the adjoint...

I'm confused about index calculation in eq. 8.25, Mandl QFT textbook. Can anyone give me a detailed explanation showing the equality below? X=\frac{1}{2}A_{\delta \alpha}^+(\bf{p'})\Gamma_{\alpha \beta}(\bf{p'})A_{\beta \gamma}^+(\bf{p})\widetilde{\Gamma}_{\gamma\delta}...

Homework Statement given \mid \psi \rangle = \frac{1}{\sqrt{2}} (\mid1\rangle + \mid2\rangle ) where \mid1\rangle, \mid2\rangle are orthonormal calculate i)density operator ii) \langle A \rangle where A is an observable Homework Equations The Attempt at a Solution i) \rho = \frac{1}{2}...

Homework Statement If U is a 2 x 2 unitary matrix with detU=1. Show that |TrU|≤2. Write down the explicit form ofU when TrU=±2 Homework Equations Not aware of any particular equations other than the definition of the determinant and trace. The Attempt at a Solution I have...

Homework Statement Could someone guide me to proof following equation. For any A is a tensor; a, b, c are vectors. Proof that: Tr (A) a.(b x c) = Aa.(b x c) + a.(Ab x c) + a. (b x Ac) with (.) is dot product, and (x) is cross product of vector Homework Equations The...

Let A, B be matrices with components Aμν , Bμν such that μ, ν = 0, 1, 2, 3. Indices are lowered and raised with the metric gμν and its inverse gμν. Find the trace of ABA-1 in component form? Since A and B are generalized versions of tensors, finding their inverse becomes very tedious if we try...

Hi Let D be an anisotropic tensor. This means especially, that D is traceless. \mathrm{tr}(D) = 0 Apply the representating matrix of D to a basis vector S , get a new vector and multiply this by dot product to your basis vector. Than you got a scalar function. Now integrate this...

one-point compactification of space of matrices with non-negative trace Hi I'm a physicist and my question is a bit text-bookey but it is also part of the proof that the universe had a beginning...so could I ask anyway...You got q which is a continuous function of a 3 by 3 matrix where if any...

T:V -> V is linear. V is finite vectorspace of dimension m^2. T(M) = AMB where M is an mXm matrix and A, B are two fixed mXm matrices. I want to find the trace and determinant of this transformation. In the case where B is the indentity, I can show that the trace is m*tr(A) and the...

I'm currently reading "Introduction to tensors and Group Theory for Physicists". I'm stuck on a question posed on dual spaces. The author gives the trace as an example of a linear functional on the vector space M_n(ℝ) (n x n matrices with real entries) and then asks how one would find the...

Homework Statement Prove that for any matrix A, the following relation is true: det(e^{A})=e^{tr(A)} The Attempt at a Solution PROOF: Let A be in Jordan Canonical form, then A=PDP^{-1} where D is the diagonal matrix whose entries are the eigenvalues of A. Then...

for dimension 2, the following relation between determinant and trace of a square matrix A is true: det A=((Tr A)2-Tr (A2))/2 for dimension 3 a similar identity can be found in http://en.wikipedia.org/wiki/Determinant Does anyone know the generalization to dimension 4 ? lukluk

Hi, I am not able to understand something about partial tracing. We have a quantum state \rho_{AB}. The Hilbert Space is H_{A}\otimes H_{B}. For some observable A in H_{A}, we have Tr_{A}(\rho_{A}A)=Tr_{AB}(\rho_{AB}(A\otimes 1)) =\sum\sum<a_{j}, b_{k}|\rho_{AB}(A\otimes 1_{B})|a_{j}, b_{k}>...

Hi, Let T_{\alpha\beta} be the stress-energy momentum tensor. What does g_{\alpha\beta}T^{\alpha\beta} mean? I have always thought of the Ricci tensor and the SEM as the same thing essentially, but the Ricci scalar essentially assigns a number to the curvature of the manifold, what does T...

How does knowing that two matrices anticommute AB=-BA and that A^2=1 and B^2=1 help me to know how to find the trace of the matrices. I am supposed to show that their traces equal each other which equals 0 but I am not sure exactly how the given information helps me determine the trace?

Homework Statement A dog is at a distance L due north of a rabbit. He starts to pursue the rabbit and its motion always points to the rabbit. Given that the rabbit keeps running due east with a constant speed v and the dog's speed is a constant u, where v<u. Find the time that the dog catches...

Hi, The Quantum Liouville Equation is \dot{\rho} = \frac{i}{\hbar}[\rho, H] where the dot denotes the partial derivative with respect to time t. We take \hbar = 1 hereafter for convenience. Tr(\dot{\rho}) = 0 Consider Tr(\rho^2) Differentiating with respect to time...

Hope this is the right section. I'm having trouble ironing out an apparent inconsistency in matrix trace derivative rules. Two particular rules for matrix trace derivatives are \frac{\partial}{\partial\mathbf{X}} Tr(\mathbf{X}^2\mathbf{A})=(\mathbf{X} \mathbf{A}+\mathbf{A} \mathbf{X})^T...

i need to prove that if tr(A^2)=0 then A=0 we have a multiplication of 2 the same simmetrical matrices why there multiplication is this sum formula A*A=\sum_{k=1}^{n}a_{ik}a_{kj} i know that wjen we multiply two matrices then in our result matrix each aij...

Why is the Trace of a projection is its Rank. Thank you

In many books and also in wikipedia, the Trace of a matrix is defined as sum of its diagonal elements. For a general matrix, it does not make much sense, as any element is as important any other element. An alternative definition (in wikipedia for example) is that the Trace of the matrix...

Okay so I have: Eqn1) Tij=\rhouiuj-phij = \rhouiuj-p(gij-uiuj) Where Tij is the energy-momentum tensor, being approximated as a fluid with \rho as the energy density and p as the pressure in the medium. My problem: Eqn2) Trace(T) = Tii = gijTij = \rho-3p My attempt: Tr(T) = Tii...

At least 3 million years are required to form a geological strata (of say 7 ft?). What remanents of a culture might survive? Plastic pieces; or nothing at all? Our world has hundreds of tons of plutonium; plus all reactors forming plutonium. The halve life of plutonium is very long...

I think I'm missing something real simple on trace theorems and Dirac matrices, but am just not seeing it. In the Peskin and Schroeder QFT text on page 135 we have: gamma^(mu)*gamma^(nu)*gamma_(mu) = -2*gamma^(nu) But, why can't we anti-commute and obtain the following...

I would like to ask, how these identities are true \partial_{\mu}(-g)=(-g)g^{\alpha\beta}\partial_{\mu}g_{\alpha\beta} and \partial_{\mu}g^{\alpha\beta}=-g^{\alpha\lambda}g^{\beta\rho}\partial_{\mu}g_{\lambda\rho} Sorry I meant" derivative of metric tensor and its determinant", I was able to...

Homework Statement Let X denote the set of all real symmetric 3x3 matrices. The trace of a matrix, tr(x) is defined as the sum of the diagonal components and is a linear function. Define L(x) = tr(x), where x refers to X. Find the representation of this operator with respect to a basis set for...

Given a function f(X)= Tr(X'AX) - 2Tr(X'BC), with X' denoting matrix transpose, I'm supposed to find the expression used to miminize the function with respect to X. The derivatives should be used, but I'm not sure how to proceed. Any help is appreciated.

How can I show that trace is Invariant under the change of basis?

Not a Homework problem, but I think it belongs here. Homework Statement Consider four dirac matrices that obey M_i M_j + M_j M_i = 2 \delta_{ij} I knowing the property that Tr ABC = Tr CAB = Tr BCA show that the matrices are traceless. Homework Equations Tr MN = Tr NM The Attempt...

The integral: \int \Pi_k d\phi_k e^{-\phi_i A_{ij} \phi_j} is a Gaussian and is equal to: (\pi)^{n/2}\sqrt{det(A^{-1})}= (\pi)^{n/2} e^{\frac{1}{2}Tr ln A^{-1}} Now usually A is a diagonal matrix that represents the Lagrangian (so that the sum over i and j collapses to a sum just over i...

FInd the determinant of the following matrix? 4,-4,-8 -2, 2, 6 0, 0,-1 Heres my attempt 4.(2x(-1)- 6x0) -(-4).((-2)x(-1) - 6x0) +(-8).((-2)x0-2x0) which goves: 4.(-2)+4(2) -8 = 0 is this correct?? Im also asked to find the trace? What is this and how do i find it...

Let V=Mn(k) be a vector space of matrices with entries in k. For a matrix M denote the trace of M by tr(M). What is the dimension of the subspace of {M\inV: tr(M)=0} I know that I am supposed to use the rank-nullity theorem. However I'm not sure exactly how to use it. I know that the trace is...

Homework Statement What is the nullity of the trace (A), A is an element of all nxn square matrices. The Attempt at a Solution the null space would be when the sum of the diagonal is equal to 0. So the Σaii for i=1 to n must equal 0 which would be when aii = -aii. Therefore the...

If I have a trace on a PCB that is wider on the left side and then tapers down to a narrower trace on the right side, why is it that the inductance is greater on the narrower side? I realize there are equations that describe this behavior but I'm just trying to get a qualitative understanding of...

I have some math questions about quantum theory that have been bugging me for a while, and I haven't found a suitable answer in my own resources. I'll start with the Trace operation. Question A) My understanding is that if we take system A and perform the partial trace over system B, we...

so i came up with a proof that..well.. Let L/K be a field extension and we have defined the norm and trace of an element in L, call it a, to be the determinant (resp. trace) of the linear transformation L -> L given by x->ax. Now it's well known that the determinant and trace are the...

regarding the density of states: how I GET THE FOLLOWING EQUALITY? \langle E_n\mid \delta(E-\widehat{H}) \mid E_n \rangle = \sum_n \delta(E-E_n)

Hi. So I have learned that this holds for the trace if A and B are two operators: \text{Tr}(AB)=\text{Tr}(BA). Now I take the trace of the commutator between x and p: \text{Tr}(xp)-\text{Tr}(px)=\text{Tr}(xp)-\text{Tr}(xp)=0. But the commutator of x and p is i\hbar. Certainly the trace of...

Let us consider the Electric field components of a polarized EM wave . [PLAIN]http://www.cdeep.iitb.ac.in/nptel/Electrical%20&%20Comm%20Engg/Transmission%20Lines%20and%20EM%20Waves/graphics/CHAP%204__255.png. Now if we fix the value of z (for convenience take z=0) and consider the locus of...

Hi... We have all seen the equation det(M)=exp(tr(lnM)). I was taught the proof using diagonalisation. I was wondering if there was a proof for non-diagonalisable matrices also.

Can someone help me prove that tr(\rho^2) \leq 1 ? Using that \rho = \sum_i p_i | \psi_i \rangle \langle \psi_i | \rho^2 = \sum_i p_i^2 | \psi_i \rangle \langle \psi_i | tr(\rho^2) = \sum_{i, j} p_i^2 \langle j | \psi_i \rangle \langle \psi_i | j \rangle Where do I go from here? Thanks guys.

Use the trace and determinant to compute eigenvalues. I know how to do this with a 2x2 but not sure how to do it with a matrix of nxn where n>2. \begin{bmatrix} \frac{1}{2} & \frac{1}{3} & \frac{1}{5}\\ \frac{1}{4} & \frac{1}{3} & \frac{2}{5}\\ \frac{1}{4} & \frac{1}{3} & \frac{2}{5}...

Homework Statement I was asked to find Tr q (p + m) q (p + m) Homework Equations Tr p q = 4pq The Attempt at a Solution If I expand it as Tr (p q p q + m q p q + m q q p + (m^2)(q)^2 ), although Tr Π(odd number of gamma matrices) = 0, since q p q and similar terms are not square...

Hey guys, any hints on how to show that \frac{d}{dt}|t=0 det(I + tA) = tr(A) ? I did it for 2x2 but I can't figure out a generalization. Thanks

Well, not every plane, just those equipped with ADS-B. Still, fun to check what it is flying over your house. http://www.flightradar24.com/

Does anyone know where to find this paper? Formule de trace en géométrie non-commutative et hypothèse de Riemann = Trace formula in noncommutative geometry and the Riemann hypothesis http://cat.inist.fr/?aModele=afficheN&cpsidt=2561461 The purchase link is broken there.. it gets stuck...

Hi, I came across a line (http://www.springerlink.com/content/t523l30514754578/) about how the trace of a linear operator is not, in general, independent of the choice of orthonormal basis. The link states that such an operator may have a trace that converges for one basis but not another...

Homework Statement Show that the trace functional on n X n matrices is unique in the following sense. If W is the space of n X n matrices over the field F and if f is a linear functional on W such that f(AB) = f(BA) for each A and B in W, then f is a scalar multiple of the trace function. If...

Dear All I'd be very grateful if someone could help me out with finding the trace of a product of 4 SL(2,C) matrices, namely: \mathrm{Tr} \left[ \sigma^{\alpha} \sigma^{\beta} \sigma^{\gamma} \sigma^{\delta} \right] where: \sigma^{\alpha} = (\sigma^0, \sigma^1, \sigma^2, \sigma^3)...