Superconducting qubits – an introduction

In some of the last posts in my series on quantum computing, we have discussed how NMR (nuclear magnetic resonance) technology can be used to implement quantum computers. Over the last couple of years, however, a different technology has attracted significantly more interest and invest - superconducting qubits. What are superconducting qubits? To start with … Continue reading Superconducting qubits – an introduction

Quantum teleportation

Quantum states are in many ways different from information stored in classical systems - quantum states cannot be cloned and quantum information cannot be erased. However, it turns out that quantum information can be transmitted and replicated by combining a quantum channel and a classical channel - a process known as quantum teleportation. Bell states … Continue reading Quantum teleportation

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 error correction: an introduction to toric codes

While playing with the IBM Q experience in some of my recent posts, we have seen that real qubits are subject to geometric restrictions - two-qubit gates cannot involve arbitrary qubits, but only qubits that are in some sense neighbors. This suggests that efficient error correction codes need to tie to the geometry of the … Continue reading Quantum error correction: an introduction to toric codes