Operating on an MPO from the right

ITensor Julia Questions
1

Hi,

Is it possible to operate on an MPO from both directions? It seems that the following is correct:

using ITensors, ITensorMPS

let
    s = siteinds("Qubit",2)
    
    oper = op("Rx", s[1], θ=π/5)

    mpo = MPO(s, "I")

    mpo =apply(oper, mpo)

end

However, changing the apply command to mpo = apply(mpo, oper) throws an error. In some cases it would be useful to build an MPO from both directions, not only by applying the operators naively from left to right.

2

You can use mpot = swapprime(mpo, 0 => 1) and opert = swapprime(oper, 0 => 1) to transpose the MPO and operator so that swapprime(apply(opert, mpot), 0 => 1) applies the operator on the other side (and transposes back).

Though probably we should support apply(mpo, oper) as a shorthand for that.

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3

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