## How to run big quantum circuits on small quantum computers in PennyLane

Category: how-to | Author: Radoica Draškić (Xanadu Resident)

Even with a small number of available qubits, large quantum circuits can be cut up into fragments and their results classically recombined into the desired, full computation. In this how-to we present a short introduction to making quantum circuit cuts in PennyLane.

## How to choose your device

Category: How-to | Author: Aleksei Malyshev

Have you ever wanted to befriend a quantum computer or two? Join us at the PennyLane Device Zoo, a place where everybody can find the right device for their problem and make their code fly!

## How to execute quantum circuits in collections and batches

Category: how-to | Author: Carlos E. Lopetegui Gonzalez

In this how-to, we will learn about the best practices in PennyLane to deal with batches and collections of circuits.

## How to get Device and Circuit Information

Category: how-to | Author: Anuj Apte (Xanadu resident)

The purpose of this article is to explain how to obtain information about devices and circuits using the qml.specs and qml.Tracker functions.

## How to create your own device in PennyLane

Category: how-to | Author: Maurice Weber (Xanadu resident)

In this how-to we show how to use PennyLane to create your own custom devices with a simple one-qubit example.

## How to use the Hartree-Fock method in PennyLane

Category: how-to | Author: Matija Medvidović (Xanadu resident)

Hartree-Fock is a standard classical state-preparation step for running quantum chemistry workflows. This post goes through how to make the process painless with PennyLane!

## How to embed data into a quantum state

Category: how-to | Author: Isidor Schoch (Xanadu resident)

In this how-to, we will explore a few methods to encode different types of data in a quantum computer.

## How to create your own optimizer

Category: how-to | Author: Luis Mantilla (Xanadu resident)

In quantum machine learning (QML), we need to optimize parameters of a variational quantum ansatz to minimize some specified cost function. How we choose to optimize the parameters is one of the key steps of every QML workflow. Specifically, the choice of different optimizers can highly influence the parameters obtained after an optimization routine. For this reason, in this How-to blog, we will learn how to implement our own custom-built optimizer.

## How to create and visualize a cluster state in FlamingPy

Category: how-to | Author: Joost Bus (Xanadu resident)

A short introduction to using FlamingPy for creating and visualizing cluster states that are relevant in measurement-based quantum computing.

## How to do measurements in PennyLane

Category: how-to | Author: Joana Fraxanet (Xanadu Resident)

When using PennyLane to design quantum circuits we need to consider both the sequence of gates that we want to apply and also the kind of output that we want to obtain. At the end of the day, we will get back a quantity through a specific measurement. In this how-to, we go through the different type of measurements offered by PennyLane and we discuss when to use them.

## How to choose your optimizer

Category: how-to | Author: Davide Castaldo (Xanadu resident)

Variational hybrid algorithms often task a quantum processor to prepare, parametrically, a quantum state and a classical computer to optimize these parameters. Whether you are looking for the ground state of a molecule or training a quantum neural network this how-to will guide you through the choice of the most convenient optimizer featured in PennyLane.

## How to start learning quantum machine learning

Category: how-to | Author: Catalina Albornoz (PennyLane Team)

If machine learning is interesting, quantum machine learning (QML) is twice as interesting. It’s incredible that you can combine these two fields into one, and it is an area that has seen huge interest and growth in the past few years. In this blog post we will highlight some …

## How to write quantum function transforms in PennyLane

Category: how-to | Author: Olivia Di Matteo (PennyLane Team)

Quantum transforms are an exciting new feature of PennyLane. Learn how transforms can help you construct and manipulate quantum functions with ease!

## How to perform parameter initialization of PennyLane’s built-in templates

Category: how-to | Author: Elies Gil-Fuster (Xanadu Resident)

QML algorithms often involve a set of trainable parameters, in most cases, these parameters need to be initialized in a certain fashion before, say, starting a gradient descent. In this how-to, we’ll see how to do precisely that.

## How to add custom gates and templates to PennyLane

Category: how-to | Author: David Wierichs (Xanadu Resident)

Implementing your own gates in PennyLane does not require deep manipulation of the code base but is as easy as listing some core properties of the operation to be added. Even easier, you can construct your own templates to create structured special purpose circuits and simplify your workflow.

## Using PennyLane and Strawberry Fields to run programs on Xanadu hardware

Category: how-to | Author: Jack Ceroni (Xanadu Resident)

One of the advantages of PennyLane is that it can be run on many different simulators and real quantum devices from a variety of external providers through our Plugins, as well as Xanadu’s own devices! In this how-to, we will show you how to create a simple program in …

## How to visualize quantum circuits in PennyLane

Category: how-to | Author: Yuan Yao (Xanadu Resident)

Already built your fancy quantum circuit and wanna have a look at it? PennyLane supports visualizing quantum circuits once you have defined them.

## How to simulate noise with PennyLane

Category: how-to | Author: David Wakeham (Xanadu resident)

Near-term quantum devices are noisy, a fact we need to account for in our simulations. In this how-to guide, we give three simple methods for simulating noise: classical jitter, built-in PennyLane support for mixed states and quantum channels, and finally plugins to Cirq and Qiskit.

## How to construct and load Hamiltonians in PennyLane

Category: how-to | Author: Roeland Wiersema (Xanadu Resident)

Constructing different types of Hamiltonians is easy in Pennylane. In this how-to, we will show you how to easily create Hamiltonians for problems in combinatorial optimization, quantum many-body physics and quantum chemistry.

## How to parallelize QNode execution

Category: how-to | Author: Brian Doolittle (Xanadu resident)

In PennyLane, QNodeCollection execution can be parallelized across remote devices. In this how-to guide, we demonstrate the advantage of parallel execution through the example of qubit state tomography.

## How to build a model with chained QNodes

Category: how-to | Author: Josh Izaac (PennyLane team)

In PennyLane, we can easily construct VQE and QAOA-like models. However, the flexibility of PennyLane allows much more interesting models to be constructed. In this how-to, we’ll show you how to chain two QNodes together.

## How to calculate the Hessian of a classical-quantum hybrid model

Category: how-to | Author: Josh Izaac (PennyLane Team)

PennyLane QNodes don’t just support computing the derivative—they also support computing the second derivative. Further, the second derivative can be computed on both simulators and quantum hardware. In this how-to, we’ll show you how you can extract the Hessian of a hybrid model using PennyLane in three …