Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Retro-information implies quantum unitary violation

Philippe Jacquet, Veronique Joly

Published Feb 4, 2024• 0 citations
OpenAlex

Abstract

We prove simple theorems around the impossibility of sending information backward in time without the violation of the principle of quantum unitarity in physics. The result also extends to faster than light information transfer. The theorem is comparable to the "no-cloning" theorem, which we generalize. This result is a kind of reciprocal of the author former result which proved that a repetitive unitary violation would make possible retro-information.

Related papers

Stronger no-cloning, no-signalling and conservation of quantum information

Indranil Chakrabarty, Arun Kumar Pati, Satyabrata Adhikari

It is known that the stronger no-cloning theorem and the no-deleting theorem taken together provide the permanence property of quantum information. Also, it is known that the violation of the no-deletion theorem would imply signalling. Here, we show that the violation of the stronger no-cloning theorem could lead to signalling. Furthermore, we prove the stronger no-cloning theorem from the conservation of quantum information. These observations imply that the permanence property of quantum information is connected to the no-signalling and the conservation of quantum information.

arXiv:quant-ph/0605173•May 19, 2006•0 citations

Faster-Than-Light Communication using Quantum Entanglement is Possible

Florentín Smarandache

In this little note we refute the statement that Faster-Than-Light Communication using Quantum Entanglement is Impossible, by proving that the alleged proof of the mainstream is irrelevant. Also, the Faster-Than-Light Communication does NOT mean sending information into the past. We recall the many paradoxes of the theory of relativity that make it unrealistic, while the Absolute Theory of Relativity [1] is the realistic one.

Information Sciences with Applications•Dec 19, 2025•0 citations

No-cloning with unitary scaling

Dafa Li

It is known that the classical information like strings of bits can be copied. In 1982, Wootters and Zurek proposed the quantum no-cloning principle. No-cloning principle says that it is impossible to make an identical copy of an arbitrary unknown quantum pure state by using unitary evolution. In this paper, we call U $|ψ>$, where U is any unitary operator, a U-copy of the state $|ψ>$ and show it is impossible to make a U-copy of an arbitrary unknown quantum pure state by using unitary evolution.

quant-pharXiv:2604.22960•Apr 28, 2026•0 citations

Questioning the correctness of quantum no-cloning theorem

Yong Wang

The paper queries correctness of quantum no-cloning theorem that is very imporant in the quantum information technology and the whole quantum mechanics.The proof of quantum no-cloning theorem is very simple and it can’t exclude all kinds of possible cloning.Some parts of the proof are doubtful and not very clearly proved.While quantum mechanics is very complex and not completely known,the principle of complementarity shows that it is incorrect to explain everything in a simple way.The development of science tells us many things such as measurement and copy of a particle that are thought to be impossible in a stage,may be possible when the more profound,precise and tiny characteristics is found out.If it is possible to measure in an indirect way that can’t change the measured quantum state,the quantum cloning is possible.The wave-particle duality and uncertainty relation in quantum mechanics are very hard to imagine,but they are very similar to the phenomenon of the society and human in which copy and cloning is possible.If the quantum state has something like gene,it is possible to cloning a quantum state.

Infrared and Laser Engineering•Jan 1, 2007•1 citation

Retro-information implies quantum unitary violation even in absence of Closed Time Curves

Philippe Jacquet, Veronique Joly

Time travel is a popular topic in science fiction. In general the support is the so-called Closed Time Curves (CTC) as they are predicted by general relativity [1, 2]. However time travel meets a logical impossibility because of the grandfather paradox.

•Jul 7, 2024•0 citations

Introducing Quantum Error Correction

Steven H. Simon

Abstract We briefly introduce some basic ideas of information and quantum information. We start by comparing a classical memory with a quantum memory. Simple repetition codes can protect classical memories from error and we introduce the idea of a code space, physical bits, and logical bits. However, the quantum no-cloning theorem prevents a straightforward generalization to the quantum case. Nonetheless quantum error correction is indeed possible. We show the 9 qubit Shor code as an example.

•Sep 29, 2023•0 citations
We prove simple theorems around the impossibility of sending information backward in time without the violation of the principle of quantum unitarity in physics. The result also extends to faster than light information transfer. The theorem is comparable to the "no-cloning" theorem, which we generalize. This result is a kind of reciprocal of the author former result which proved that a repetitive unitary violation would make possible retro-information.
It is known that the stronger no-cloning theorem and the no-deleting theorem taken together provide the permanence property of quantum information. Also, it is known that the violation of the no-deletion theorem would imply signalling. Here, we show that the violation of the stronger no-cloning theorem could lead to signalling. Furthermore, we prove the stronger no-cloning theorem from the conservation of quantum information. These observations imply that the permanence property of quantum information is connected to the no-signalling and the conservation of quantum information.
It is known that the classical information like strings of bits can be copied. In 1982, Wootters and Zurek proposed the quantum no-cloning principle. No-cloning principle says that it is impossible to make an identical copy of an arbitrary unknown quantum pure state by using unitary evolution. In this paper, we call U ∣ψ>|ψ>∣ψ>, where U is any unitary operator, a U-copy of the state ∣ψ>|ψ>∣ψ> and show it is impossible to make a U-copy of an arbitrary unknown quantum pure state by using unitary evolution.
The paper queries correctness of quantum no-cloning theorem that is very imporant in the quantum information technology and the whole quantum mechanics.The proof of quantum no-cloning theorem is very simple and it can’t exclude all kinds of possible cloning.Some parts of the proof are doubtful and not very clearly proved.While quantum mechanics is very complex and not completely known,the principle of complementarity shows that it is incorrect to explain everything in a simple way.The development of science tells us many things such as measurement and copy of a particle that are thought to be impossible in a stage,may be possible when the more profound,precise and tiny characteristics is found out.If it is possible to measure in an indirect way that can’t change the measured quantum state,the quantum cloning is possible.The wave-particle duality and uncertainty relation in quantum mechanics are very hard to imagine,but they are very similar to the phenomenon of the society and human in which copy and cloning is possible.If the quantum state has something like gene,it is possible to cloning a quantum state.