Sharing a secret...the quantum way

Date:
July 31, 2020
Source:
University of the Witwatersrand
Summary:
Researchers have demonstrated a record setting quantum protocol
for sharing a secret amongst many parties.



FULL STORY ========================================================================== Researchers at the University of the Witwatersrand in Johannesburg,
South Africa, have demonstrated a record setting quantum protocol for
sharing a secret amongst many parties. The team created an 11-dimensional quantum state and used it to share a secret amongst 10 parties. By using quantum tricks, the secret can only be unlocked if the parties trust
one another. The work sets a new record for the dimension of the state
(which impacts on how big the secret can be) and the number of parties
with whom it is shared and is an important step towards distributing information securely across many nodes in a quantum network.


========================================================================== Laser & Photonics Reviews published online the research by the Wits
team led by Professor Andrew Forbes from the School of Physics at
Wits University. In their paper titled: Experimental Demonstration of 11-Dimensional 10-Party Quantum Secret Sharing, the Wits team beat all
prior records to share a quantum secret.

"In traditional secure quantum communication, information is sent securely
from one party to another, often named Alice and Bob. In the language
of networks, this would be considered peer-to-peer communication and by definition has only the two nodes: sender and receiver," says Forbes.

"Anyone who has sent an email will know that often information must be
sent to several people: one sender and many receiving parties. Traditional quantum communication such as quantum key distribution (QKD) does not
allow this, and is only of the peer-to-peer form." Using structured
light as quantum photon states, the Wits team showed how to distribute information from one sender to 10 parties. Then, by using some nifty
quantum tricks, they could engineer the protocol so that only if the
parties trust one another can the secret be revealed.

"In essence, each party has no useful information, but if they trust one another then the secret can be revealed. The level of trust can be set
from just a few of the parties to all of them," says Forbes. Importantly,
at no stage is the secret ever revealed through communication between
the parties: they don't have to reveal any secrets. In this way a secret
can be shared in a fundamentally secure manner across many nodes of a
network: quantum secret sharing.

"Our work pushes the state-of-the-art and brings quantum communication
closer to true network implementation," says Forbes. "When you think of networks you think of many connections, many parties, who wish to share information and not just two. Now we know how to do this the quantum way."
The team used structured photons to reach high dimensions. Structured
light means ''Patterns of light" and here the team could use many patterns
to push the dimension limit. More dimensions mean more information in
the light, and translates directly to larger secrets.


========================================================================== Story Source: Materials provided by University_of_the_Witwatersrand. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jonathan Pinnell, Isaac Nape, Michael Oliveira, Najmeh TabeBordbar,
Andrew Forbes. Experimental Demonstration of 11‐Dimensional
10‐Party Quantum Secret Sharing. Laser & Photonics Reviews,
2020; 2000012 DOI: 10.1002/lpor.202000012 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200731102631.htm

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