Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relaxation in quantum dots due to evanescent-wave Johnson noise from a
  metallic backgate   We present our study of decoherence in charge (spin) qubits due to
evanescent-wave Johnson noise (EWJN) in a laterally coupled double quantum dot
(single quantum dot). The high density of evanescent modes in the vicinity of
metallic gates causes energy relaxation and a loss of phase coherence of
electrons trapped in quantum dots. We derive expressions for the resultant
energy relaxation rates of charge and spin qubits in a variety of dot
geometries, and EWJN is shown to be a dominant source of decoherence for spin
qubits held at low magnetic fields. Previous studies in this field approximated
the charge or spin qubit as a point dipole. Ignoring the finite size of the
quantum dot in this way leads to a spurious divergence in the relaxation rate
as the qubit approaches the metal. Our approach goes beyond the dipole
approximation and remedies this unphysical divergence by taking into account
the finite size of the quantum dot. Additionally, we derive an enhancement of
EWJN that occurs outside a thin metallic film, relative to the field
surrounding a conducting half-space.

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The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol