**Guest blog by Dr Beni Yoshida, quantum information fellow at Caltech**

The lessons we learned from the Ryu-Takayanagi formula, the firewall paradox, and the ER=EPR conjecture have convinced us that quantum information theory can become a powerful tool to sharpen our understanding of various problems in high-energy physics. But many of the concepts utilized so far rely on entanglement entropy and its generalizations, quantities developed by Von Neumann more than 60 years ago. We live in the 21st century. Why don’t we use more modern concepts, such as the theory of quantum error-correcting codes?

In a recentOff-topic, LHC:CERN sent quite some current to the shorted segment of the circuit, apparently melted and destroyed the offending metallic piece in a diode box, and miraculously cured the LHC! Restart could be within days. LM

**paper with Daniel Harlow, Fernando Pastawski and John Preskill**, we have proposed a toy model of the AdS/CFT correspondence based on quantum error-correcting codes. Fernando has already written how this research project started after a fateful visit by Daniel to Caltech and John’s remarkable prediction in 1999. In this post, I hope to write an introduction which may serve as a reader’s guide to our paper, explaining why I’m so fascinated by the beauty of the toy model.

The background is temporarily "nearly white" today because I celebrate the Kilowatt Hour, also known as the Electricity Thanksgiving Day. Between 8:30 and 9:30 pm local time, turn all your electric appliances on and try to surpass one kilowatt. By this $0.20 sacrifice, you will fight those who want to return us to the Middle Ages and who organize the so-called Earth Hour.