<p>As of QISKit v0.4.9, the <a href="https://www.qiskit.org/documentation/_autodoc/qiskit.extensions.standard.html#qiskit.extensions.standard.u3" rel="nofollow noreferrer"><code>u3()</code></a> function parametrizes an arbitrary single-qubit unitary gate <em>U(θ, φ, λ)</em> (for details, <a href="https://arxiv.org/pdf/1707.03429.pdf" rel="nofollow noreferrer">see</a> formula (2)). Obviously, you can use the <code>u3()</code> function to set a qubit to any value.</p>

<p>For example, this is how you can implement the <em>X</em>-gate and apply it to some qubit <code>qr[0]</code> via the <em>U3</em>-gate:</p>

<pre class="lang-python prettyprint-override"><code>u3(theta=math.pi, phi=0, lam=0, q=qr[0])
</code></pre>
How to create a new quantum gate and qubit initialised to a certain value
<p>I am trying to implement the Quantum HHL algorithm on QISKit package of IBM on Python. I have tried searching the documentation for a method to initialize a  qubit to a certain value and to create a new unitary gate with specified values. </p>

<p>In the documentation, I found <a href="https://github.com/QISKit/qiskit-sdk-py/blob/master/qiskit/_gate.py" rel="nofollow noreferrer">this</a>, which is the class of a Quantum Gate. I tried to make a new instance of this class but I couldn't because not much documentation has been done about the arguments to be passed while initializing the instance of the class. </p>