Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Implementing universal multi-qubit quantum logic gates in three and
  four-spin systems at room temperature   In this paper, we present the experimental realization of multi-qubit gates
$% \Lambda_n(not) $ in macroscopic ensemble of three-qubit and four-qubit
molecules. Instead of depending heavily on the two-bit universal gate, which
served as the basic quantum operation in quantum computing, we use pulses of
well-defined frequency and length that simultaneously apply to all qubits in a
quantum register. It appears that this method is experimentally convenient when
this procedure is extended to more qubits on some quantum computation, and it
can also be used in other physical systems.

6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
18
The categories of this paper are: econ
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org