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Unlike several rising branches of computer science such as artificial intellgence and machine learning, quantum computing is still young when it comes to the development level. Most widely used quantum programming languages and libraries are created for people to learn and experiment with their ideas rather than for publishing any kind of commercial product. Generally speaking, the field has a weak application side; its focus strongly lies in interpreting quantum information theories and… build some funny stuffs for the sake of learning. ...

Who am I and what the fish is this blog?

About me Hi, my name is Entangled, a cat who adopted a boy named Trong, my hooman slave… I liken’t when he laughed watching videos of other cats showing off their cuteness. He’s textroverted that is apparently energetic in a texting conversation but may dumb as a fish in a face-to-face. Just send him cat footages to get him engaged. Okay, here’s the truth. He’s a coming student at KAIST (Korean Advanced Institute of Science and Technology) and inclined to major in Physics plus Computer Science. ...

#project #Teleportation

Quantum Teleportation (Part 3): Implementation

Let’s implement and verify the teleporation protocol following the procedure we discussed throughout previous parts. First we need to create an arbitrary quantum state. Trong has been curious about the combined effect of rotation gates about the x, y, and z axes. So, he decides to apply three distinct rotation gates, each as a rotation of 60 degrees around one coordinate axis acting on a qubit currently in the Hadamard state $|-\rangle$. ...

#Teleportation

Quantum Teleportation (Part 2): The Art of transporting the Unknown

Problem Statement Suppose Trong has just created a wonderful qubit in his lab. He knows his qubit look like $|\psi\rangle = \alpha |0\rangle + \beta |1\rangle$ but doesn’t know $\alpha$ and $\beta$. Now he wants to transport this qubit to his crush, but they don’t have a quantum channel that can help transport quantum information. Of course it’s a very bad idea for Trong to try to figure out $\alpha$ and $\beta$ through measurement because if he does so, he’ll destroy his qubit but only learn extremely little information about it. ...

#Teleportation

Quantum Teleportation (Part 1): Preliminaries

Here we start exploring a core of Quantum Computing: Quantum Algorithms. Before we dive into the dark and deep pool of such algorithms, it’s helpful to get familiar with a fundamental constraint to Quantum Computing. In contrast, I’ll also introduce you how powerful qubits get in solving problems through a basic protocol: Quantum Teleportation, the “Hello, world!” of Quantum Programming. No-cloning theorem In terms of computer architechture, it’s convenient to copy the state of a bit in order to create a new qubit exactly the same. ...

#Quantum Mechanics

A formal approach to Observables and Measurements

Throughout previous posts, I’ve delivered a way to understand what is a quantum measurement. That way of understanding is simple and may suit our normal intuition, but measurement is a non-trivial physical process and somewhat counter-intuitive for several reasons. First, a measurement in general results in probabilistic outcomes. No matter how careful you prepare for the measurement procedure, it is inherent that possible outcomes of a measure is distributed according to a certain probability distribution determined by the state space of your quantum system. ...