A blog written by quantum researchers for quantum researchers and those interested in their work.

It looks like 2015 is the year of the loophole-free Bell test. Three different papers, with three very different p-values, all claim to put the final nail in the local-realistic coffin. I will compare the designs and results of the three experiments with an eye towards their strengths and weaknesses.[1] The three papers are, in order of experiment completion:

In Part 1 of this series I made the bold claim that, unlike what famous figures in science seemed to suggest, quantum mechanics is a beautiful and simple theory that is accessible to anyone who is enthusiastic about learning it. In Part 2, I am going to put my money where my mouth is and teach you the *basics* of quantum mechanics in four short lessons. Sound good?

Before we begin, there are two important points I need to clarify.

When I was a kid, I remember watching “Entrapment”, the 1999 movie where Catherine Zeta-Jones crawls through an intricate laser maze to steal a priceless art piece. Assisted by none other than Sean Connery, who plays a notorious thief specialized in international art, she defies the laser security system and returns with the prize. But for me, it was even better.

Pixar’s delightful movie *Ratatouille* – an animated film inspired by the world of French haute cuisine – features two characters with opposing views on cooking. On one hand we have Gusteau, a jolly and chubby chef with an optimistic message that he constantly repeats in his books and TV shows:

今日は Konnichiwa!

The 5^{th} International conference on quantum cryptography (QCrypt) was held this year in beautiful Tokyo, Japan. QCrypt is the largest conference to focus entirely on quantum cryptography and it routinely gathers all the best researchers in the field from around the world.

A quantum state \(\rho\) that is shared between two parties is called *separable* if it can be written as a convex combination of local quantum states \(\{\sigma_i\}\) and \(\{\tau_i\}\):

\[\rho = \sum_i p_i \sigma_i \otimes \tau_i.\]

States that are not separable are called entangled, and the distinction between these two types of states is important because there are many senses in which entangled states are exactly the "useful" ones in quantum information theory.

During the period of June 8 - June 11 2015, the Institute for Quantum Computing (IQC) hosted the Quantum Programming and Circuits Workshop. The workshop constituted a rare opportunity to bring together researchers from both quantum computing and classical programming languages.

The belief that quantum computation is possible in practice is founded strongly on a set of theorems that are generally called ‘the’ Threshold Theorem for Fault-Tolerant Quantum Computation. Though there is non-trivial variation between threshold theorems based on differing assumptions about the errors that will affect the quantum computer, the essential content of ‘the’ theorem is that errors can be efficiently corrected if they are small enough.

On Wednesday, they brought in a performer on stilts to wander amongst the conference attendees. She was surrounded in rings of multi-coloured LEDs, costumed to look very much like what people thought the future would look like in the eighties. She twirled two torches which projected a United Nations-sanctioned logo for the International Year of Light, as if challenging Lady Liberty to step up her game.

About six weeks ago I was fortunate to attend the annual Canadian Association of Physicists (CAP) Annual Congress. This conference is organized each year at universities across the country and this year it was hosted at the University of Alberta in Edmonton, Alberta from June 15-19.

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