In my previous post on superconducting qubits, we have seen how a flux qubit represents a qubits state as a superposition of currents in a superconducting loop. Even though flux qubits have been implemented and used successfully, most research groups today focus on different types of qubits using a charge qubit as an archetype. Charge … Continue reading Superconducting qubits – on islands, charge qubits and the transmon

# Tag: Physics

# Superconducting qubits – the flux qubit

In the last post, we have discussed the basic idea of superconducting qubits - implement circuits in which a supercurrent flows that can be described by a quantum mechanical wave function, and use two energy levels of the resulting quantum system as a qubit. Today, we will look in some more detail into one possible … Continue reading Superconducting qubits – the flux qubit

# NMR based quantum computing: gates and state preparation

In my last post on NMR based quantum computing, we have seen how an individual qubit can be implemented based on NMR technology. However, just having a single qubit is of course not really helpful - what we are still missing is the ability to initialize several qubits and to realize interacting quantum gates. These … Continue reading NMR based quantum computing: gates and state preparation

# Single qubit NMR based quantum computation

In the previous post, we have sketched the basic ideas behind NMR based quantum computation. In this post, we will discuss single qubits and single qubit operations in more depth. The rotating frame of reference In NMR based quantum computing, quantum gates are realized by applying oscillating magnetic fields to our probe. As an oscillating … Continue reading Single qubit NMR based quantum computation

# Bulk quantum computing with nuclear spin systems

The theoretical foundations of universal quantum computing were essentially developed in the nineties of the last century, when the first native quantum algorithms and quantum error correction were discovered. Since then, physicists and computer scientists have been working on physical implementations of quantum computing. One of the first options that moved into the focus was … Continue reading Bulk quantum computing with nuclear spin systems

# Quantum simulation

In his famous lecture Simulating Physics with computers, Nobel laureate Richard Feynman argued that non-trivial quantum systems cannot efficiently be simulated on a classical computer, but on a quantum computer - a claim which is widely considered to be one of the cornerstones in the development of quantum computing. Time to ask whether a universal … Continue reading Quantum simulation

# Into the quantum lab – first steps with IBMs Q experience

Even though physical implementations of quantum computers make considerable progress, it is not likely that you will have one of them under your desk in the next couple of years. Fortunately, some firms like IBM and Rigetti have decided to make some of their quantum devices available only so that you can play with them. … Continue reading Into the quantum lab – first steps with IBMs Q experience

# The Boltzmann distribution

Boltzmann machines essentially learn statistical distributions. During the training phase, we present them a data set called the sample data that follows some statistical distribution. As the weights of the model are adjusted as part of the learning algorithm, the statistical model represented by the Boltzmann machine changes, and the learning phase is successful if … Continue reading The Boltzmann distribution