Quantum Information Processing, Vol. 6, No. 4, August 2007 (© 2007)
Hybrid Quantum Cloning Machine
A. K. Pati,
B. S. Choudhury
Received February 27, 2007; accepted May 3, 2007; Published online: June 20, 2007
In this work, we introduce a special kind of quantum cloning machine called
Hybrid quantum cloning machine. The introduced Hybrid quantum cloning
machine or transformation is nothing but a combination of pre-existing quantum
cloning transformations. In this sense it creates its own identity in the ﬁeld of
quantum cloners. Hybrid quantum cloning machine can be of two types: (i) State
dependent and (ii) State independent or Universal. We study here the above two
types of Hybrid quantum cloning machines. Later we will show that the state
dependent hybrid quantum-cloning machine can be applied on only four input
states. We will also ﬁnd in this paper another asymmetric universal quantum clon-
ing machine constructed from the combination of optimal universal B–H quantum
cloning machine and universal anti-cloning machine. The ﬁdelities of the two out-
puts are different and their values lie in the neighborhood of
KEY WORDS: cloning machine; hybrid cloning machine; ﬁdelity; symmetric
cloning machine; asymmetric cloning machine.
A fundamental restriction in quantum theory is that quantum informa-
tion cannot be copied perfectly
in contrast with the information we talk
about in classical world. Similarly, it is known that quantum information
cannot be deleted against a copy.
But if we pay some price, then
approximate or exact cloning and deletion operations are possible. For
example, it does not prohibit the possibility of approximate cloning of an
Bengal Engineering and Science University, Howrah 711103, West Bengal, India.
Institute of Physics, Bhubaneswar 751005, Orissa, India.
Heritage Institute of Technology, Kolkata 107, West Bengal, India.
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