Revealed: The Physics of Sticky Tape (from Cosmos Magazine)

This article that I wrote for Cosmos Magazine in 2019 was selected for the 2020 Anthology of Best Australian Science Writing, my third guernsey in three years.

Bizarrely, it’s no long on the Cosmos website – although lots of my other stories are. They can’t explain this, so – since I am sure you’ve all been looking for it incessantly – I have found a web archive of it and posted it here for your delectation.

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Teleportation fidelity the big winner in the quantum lottery

Sophie Zhao

by Phil Dooley

Running your quantum system as a lottery turns out to be a way to improve the transmission of data via quantum teleportation.

Researchers at the Research School of Physics used a probabilistic twist to develop a new transmission protocol that set a new record in data transmission: 92 percent fidelity, which more than halves the loss in previous experiments.

The new protocol will enable encrypted data, for example in finance or military settings, to be sent with higher accuracy.

“Our protocol improves the capability of the quantum teleporter to protect fragile quantum states during long-distance transmission, making the system resilient to noise and loss,” said lead researcher Dr Sophie Jie Zhao, from the Department of Quantum Sciences and the CQC2T ARC Centre of Excellence, who is the lead author in the team’s publication in Nature Communications.

Quantum teleportation is already being used in encrypted networks. It allows information to be shared instantly between linked, or entangled, quantum objects. 

However, the entanglement between the objects can easily be destroyed by interactions with external entities. This at once makes quantum teleportation extremely secure – as any tampering instantly destroys the data transfer – but also very prone to degradation through noise due to environmental interactions.

With entanglement degradation limiting their existing teleportation’s fidelity and distance, the team set their mind to improving the teleportation efficacy by leveraging the paradoxes of the Heisenberg Uncertainty Principle.

In these experiments, the ends of the teleportation link are two photons from the same source, which creates entanglement in their properties. These photons are sent to two separate locations, untouched, which leaves their properties unknown, and able to appear in any possible state.

The signaller then gets the information to be teleported to interact with one of the photons, and measures the photon’s properties – in this case amplitude and phase – making the photon choose a state. This causes the other photon (the receiver) to instantly choose its state as well. Because the two photons are linked, information about the signaller’s experiment can be deduced by the receiver.

This deduction relies on the sender separately conveying to the receiver the result of the experiment. This does not reveal the teleported information, as it is the result of the mashup between that information and the original photon. However, this result acts as a key that allows the receiver to work backwards from the result at their end and disentangle the teleported information.

It is crucial that the sender can’t know what the teleported information is – that would constitute a measurement and collapse the quantum information, said University of Queensland researcher and CQC2T member Professor Tim Ralph.

“The information needs to be hidden in uncertainty so the sender doesn’t know exactly what they are sending. The more they know about the signal, the more they destroy it,” he said.

Quantum uncertainty resulting from the mixing of possible states can be cancelled out with the key, however uncertainty resulting from noise from entanglement degradation is harder to cancel out.

To filter this noise the team leveraged the fact that the mixed states have a Gaussian distribution. They realised that a lottery, a protocol in which a subset of the measurements was selected randomly in a way that actually narrowed the Gaussian distribution, while other measurements were randomly discarded, could help filter out noise.

“Adding an element of chance to our protocol has the effect of distilling the quantum information,” Dr Zhao said.

“The post-selection effectively biases the Gaussian distribution in favour of high-amplitude outcomes than outcomes close to the origin of phase space, hence acting as an amplifier. Since this amplification is noiseless and takes over from part of the amplification applied by the receiver in standard teleportation protocols, the teleported states suffer less from the noise added due to imperfect entanglement.”

An interesting quirk of the system is that the balance between the probabilistic factor and the noise reduction can be tuned. By simply reducing the probability of measurements being selected in the protocol the teleportation fidelity can be increased.

To achieve their record 92 percent fidelity the team used a success rate of less than one in a hundred thousand, sampling the system for around two hours.

In the new protocol, the success of the teleportation relies on the stability of the laser system, instead of being limited by environmental noise, Dr Zhao said.

“You can always get better fidelity if you are willing to sacrifice your success rate. But then you need a longer sampling time.

“If the system were stable enough to allow us to sample for say, 20 hours, then I believe we could go above 95 percent,” she said.

Originally published on ANU Physics website

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Schrodinger’s Cat – the video is now live!

Many of you have heard me play this song live, and I’ve been planning to make a video for it.  The question was, how? Enter Wasabi the WonderCat, who offered to star in the video, some gentle impulse from Dr Kip Stewart, and I had inspiration.

Finally after 10 months of hard work teaching myself to animate, here it is!

The song was born as I wondered about how Schrodinger’s cat felt about being in a box for more than 80 years. You see, he was first put there to prove a point.

The originators of the Copenhagen Interpretation, Niels Bohr and Werner
Heisenberg proposed that reality as we knew it didn’t exist, things were
blurred across multiple states, until a measurement was made.

On the other hand, Einstein and Schrodinger found this preposterous, and
to illustrate came up with the idea of the cat in the box. 

While the fame of Schrodinger’s Cat’s has spread, it didn’t really settle the debate.

I want to know, what does the cat think, being in the box for nearly a century? Surely, it’s the dogs’ turn now!

Continue Reading Schrodinger’s Cat – the video is now live!

Spyplanes, Enzymes & Alpha Centauri: Physics in the Cloud videos published

Relive the excitement of Physics in the Cloud, October 2021. Top comedy, fascinating science, a kids story and even a visit from Ziggy Stardust and his mate Alfred E Newton.

They’ll fill us in on the Breakthrough Starshot Initiative – a plan to send tiny spacecraft to the nearest star, Alpha Centauri for the first time. After launch they will be propelled towards Alpha Centauri by a hugely powerful array of lasers on earth – they’ll surf on the light waves using tiny sails.

But will they ever return?

Includes a lively Q&A session at the end of the talk, with Alessandro Tuniz and Boris Kuhlmey from University of Sydney School of Physics.

Part 1 of Spyplanes, Enzymes & Alpha Centauri: Physics in the Cloud 2021, sponsored by Australian Institute of Physics and Laboratories Credit Union.

Watch the playlist here to see the full show.

 

Continue Reading Spyplanes, Enzymes & Alpha Centauri: Physics in the Cloud videos published

Oh When the Science!

A science version of Oh When the Saints! I’m singing the hopes and dreams of every scientist. They dream of getting published, winning grants, tenure and a Nobel Prize! In my experience, to have success in science you need to clone yourself – twice. And then a bit of prayer could be handy…

More of Phil and co is at the Dramatis Scientificae website. I created the Oh When the Science video for AIP Physics in the Cloud, October 2021. Want more songs? Try a Chemistry love song about sodium chloride, or Pluto!

Apologies to Brian Schmidt, who was the original VC cited in this song (and whose name scanned better) but as this was a NSW-based show I had to switch to a selection of Sydney-based vice-chancellors. I apologiese also to Attila Brungs – whose name I eliminated due to bad scansion.

I thank the generation of musicians who brought the song into being around 100 years ago – there seems to be no single original composer, although a few have tried to claim it.

This is part of the 2021 Physics in the Pub (-Cloud, thanks to lockdown 2021) which Phil brings you in partnership with the Australian Institute of Physics NSW Branch.

Oh When the Science! sings Phil
Oh When the Science!

It was a laugh creating this video. But I drove my partner crazy – listening to me lip sync the song a thousand times… badly as you can see. I need a camera operator!!

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If you ruled the world…

shine dome

I’m honoured to have been asked to act in “What if Scientists Ruled the World” – a forum theatre piece run by Rebus Theatre for the Australian Academy of Science and Falling Walls Festival, based in Berlin

The audience has a chance to prevent disaster (which I will surely cause… cos I am scripted that way).

It’s an amazing process to build this story in a week with the talented folk from Rebus Theatre.

Join in – wherever you are in the world, and let’s work out a way to unfuck the world!

Find out more and register at the Academy of Science website.

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Using AI to study Humans Falling Over

Dr Maryam Ghahramani from University of Canberra gives a lovely talk about her work on balance in humans. Because of her humour and charisma it’s a great pub science communication about human healthThis set is also part of the Phil Up On Science – 2021 International Women’s Day in the Pub Show.

To develop your own sci comm skills with Dr Phil, visit the Science Communication training page.

Also, if you’d like a pub night about your science, find out more at the Science In the Pub page.

This set filmed March 9, 2021, at Smiths Alternative in Canberra, Australia, by Sandie Walters.

Above all, sponsored by the Faculty of Science and Technology, University of Canberra.

In conclusion,  music used is Electricity by Phil Dooley; Thing Theme by Phil Dooley and Chris Stewart.

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