Transfer of entanglement and Measurement in SQUID rings

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16 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Transfer of entanglement and
Measurement in
SQUID rings


A. Konstadopoulou
,
Z.
Ahmad Zukarnain, and A. Vourdas


Department of Computing, University of Bradford, Bradford BD7 1DP UK.




Mesoscopic Josephson systems
due to the
scalability
they offer

play an

important
role in the implementation of the hardware for quantum information processing devices.
Of particular interest is their interaction with entangled electromagnetic fields and their
potential application in the areas such as teleportation, quantum
information distribution,
quantum security etc.


In previous work we have studied the interaction of mesoscopic devices with non
-
classical electromagnetic fields
[1
, 2
]
. Furthermore, we have also studied the interaction
of a monochromatic electromagnetic
field with

two SQUID rings
[3]
taking into account
the coupling between the two SQUIDS.


In this work we study the interaction of two
-
mode entangled microwaves with
two
distant

SQUID rings (i.e. there is no coupling between the two SQUIDs). We
consider th
e Hamiltonian describing the system and study its

temporal evolution
. Each
SQUID ring is approximated as a two
-
level system interacting with one of the two mod
es
of the electromagnetic field
.
We specifically consider the case where two modes of the
electro
magnetic field are entangled and show that the corresponding Josephson currents
threading the two distant SQUID rings
(A and B)
become also entangled.


Ne
xt
,
we
consider the interaction of SQUID B with
a third
SQUID C; SQUID A
no longer interacts with B.

A
nalysis investigates what happens to the state of SQUIDs A
and C and how a measurement in C whose result is communicated classically to A,
affects the state of A.



References

1.

A.Konstadopoulou, J.M. Hollingworth, M.~Everitt, A.Vourdas, T.D. Clark and J.
F.Ralph
,
IEE Proc. Science, Meas. Tech. 148, 229, (2001).

2.

A.Konstadopoulou, J.M. Hollingworth, M.Everitt,

A.Vourdas, T.D. Clark and J.
F.Ralph, Eur. Phys. J. B32, 279 (2003).

3.

R. Migliore, A. Konstadopoulou, A. Vourdas, T.P.Spiller, and A. Messina, Phys.
Lett. A319, 67, (2003).