Deploying to main from @ openqasm/openqasm@6c91bc6 🚀

Author: levbishop

_sources/language/delays.rst.txt

@@ -329,6 +329,29 @@ require more than 150ns for all valid combinations:
     }
 
 
+Qubits can be marked as synchronized by a box using the ``nop`` keyword (see :ref:`nop`).
+This can allow the explicit synchronization of qubits at a high level, without assigning any semantics to the action of that qubit within a box.
+For example:
+
+.. code-block::
+
+   include "stdgates.inc";
+
+   stretch s;
+   box [s] {
+      // Qubits $0 and $1 are explicitly used by the `cx`.
+      cx $0, $1;
+
+      // Qubit $2 must be synchronized to $0 and $1 at the start
+      // and end of the box, but has no defined operations within
+      // the box.
+      nop $2;
+   }
+
+.. versionadded:: 3.2
+   The ``nop`` directive.
+
+
 Barrier instruction
 -------------------
 

_sources/language/insts.rst.txt

@@ -1,7 +1,7 @@
 Built-in quantum instructions
 =============================
 
-This section describes built-in non-unitary operations.
+This section describes built-in operations on qubits, including non-unitary ones.
 
 Initialization
 --------------
@@ -73,3 +73,47 @@ broadcasts to ``b[j] = measure a[j];`` for each index ``j`` into register ``a``.
    ``c[0] = measure q[0];`` while the bottom depicts measurement of an entire register using the
    statement ``c = measure q;``. The center circuit of the top row depicts measurement as the
    final operation on ``q[0]``.
+
+
+.. _nop:
+
+Explicit no-operation
+---------------------
+
+.. versionadded:: 3.2
+   The entire ``nop`` directive.
+
+The statement ``nop <qubits>;`` is an explicit no-operation on all mentioned qubits, but marks them as being "used" within a scope.
+``<qubits>`` is a comma-separated list of qubit or qubit-register operands.
+
+In the global scope this has no effect on the program operation, though a compiler must still validate the arguments.
+This has a particularly important effect on :ref:`boxed scopes <Boxed expressions>`; a ``nop`` counts as a "use" of the qubit within the ``box``, causing the qubit to be synchronized with the rest of the box at entry and exit.
+
+A ``nop`` statement is valid in exactly the places that a gate-call statement is valid.
+The operands of a ``nop`` statement must all be in scope and be of type ``qubit`` or ``qubit[n]`` for any non-negative integer ``n``.
+
+For example:
+
+.. code-block::
+
+   include "stdgates.inc";
+
+   stretch s;
+   box [s] {
+      // Qubits $0 and $1 are explicitly used by the `cx`.
+      cx $0, $1;
+
+      // Qubit $2 must be synchronized to $0 and $1 at the start
+      // and end of the box, but has no defined operations within
+      // the box.
+      nop $2;
+
+      // More than one qubit can be specified in the list.  It is
+      // not an error to duplicate qubits, nor to ``nop`` a qubit
+      // with explicit operations in this scope.
+      nop $3, $0;
+
+      // The ``nop`` statement can have zero operands, and this
+      // has no observable effect at all.
+      nop;
+   }

grammar/index.html

@@ -74,6 +74,7 @@ <h1>OpenQASM Live Specification<a class="headerlink" href="#openqasm-version-spe
 <li class="toctree-l2"><a class="reference internal" href="language/insts.html">Built-in quantum instructions</a><ul>
 <li class="toctree-l3"><a class="reference internal" href="language/insts.html#initialization">Initialization</a></li>
 <li class="toctree-l3"><a class="reference internal" href="language/insts.html#measurement">Measurement</a></li>
+<li class="toctree-l3"><a class="reference internal" href="language/insts.html#explicit-no-operation">Explicit no-operation</a></li>
 </ul>
 </li>
 <li class="toctree-l2"><a class="reference internal" href="language/classical.html">Classical instructions</a><ul>
@@ -134,7 +135,7 @@ <h1>OpenQASM Live Specification<a class="headerlink" href="#openqasm-version-spe
 </li>
 <li class="toctree-l1"><a class="reference internal" href="grammar/index.html">OpenQASM 3.0 Grammar</a></li>
 <li class="toctree-l1"><a class="reference internal" href="release_notes.html">Release Notes</a><ul>
-<li class="toctree-l2"><a class="reference internal" href="release_notes.html#spec-v3-1-0-32">spec/v3.1.0-32</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="release_notes.html#spec-v3-1-0-33">spec/v3.1.0-33</a><ul>
 <li class="toctree-l3"><a class="reference internal" href="release_notes.html#new-features">New Features</a></li>
 <li class="toctree-l3"><a class="reference internal" href="release_notes.html#upgrade-notes">Upgrade Notes</a></li>
 <li class="toctree-l3"><a class="reference internal" href="release_notes.html#bug-fixes">Bug Fixes</a></li>

index.html

@@ -351,6 +351,26 @@ <h2>Boxed expressions<a class="headerlink" href="#boxed-expressions" title="Link
 <span class="p">}</span>
 </pre></div>
 </div>
+<p>Qubits can be marked as synchronized by a box using the <code class="docutils literal notranslate"><span class="pre">nop</span></code> keyword (see <a class="reference internal" href="insts.html#nop"><span class="std std-ref">Explicit no-operation</span></a>).
+This can allow the explicit synchronization of qubits at a high level, without assigning any semantics to the action of that qubit within a box.
+For example:</p>
+<div class="highlight-qasm3 notranslate"><div class="highlight"><pre><span></span><span class="kn">include</span><span class="w"> </span><span class="s">&quot;stdgates.inc&quot;</span><span class="p">;</span>
+
+<span class="kt">stretch</span><span class="w"> </span><span class="n">s</span><span class="p">;</span>
+<span class="k">box</span><span class="w"> </span><span class="p">[</span><span class="n">s</span><span class="p">]</span><span class="w"> </span><span class="p">{</span>
+<span class="w">   </span><span class="c1">// Qubits $0 and $1 are explicitly used by the `cx`.</span>
+<span class="w">   </span><span class="n">cx</span><span class="w"> </span><span class="l">$0</span><span class="p">,</span><span class="w"> </span><span class="l">$1</span><span class="p">;</span>
+
+<span class="w">   </span><span class="c1">// Qubit $2 must be synchronized to $0 and $1 at the start</span>
+<span class="w">   </span><span class="c1">// and end of the box, but has no defined operations within</span>
+<span class="w">   </span><span class="c1">// the box.</span>
+<span class="w">   </span><span class="n">nop</span><span class="w"> </span><span class="l">$2</span><span class="p">;</span>
+<span class="p">}</span>
+</pre></div>
+</div>
+<div class="versionadded">
+<p><span class="versionmodified added">Added in version 3.2: </span>The <code class="docutils literal notranslate"><span class="pre">nop</span></code> directive.</p>
+</div>
 </section>
 <section id="barrier-instruction">
 <h2>Barrier instruction<a class="headerlink" href="#barrier-instruction" title="Link to this heading">¶</a></h2>

language/delays.html

@@ -121,6 +121,7 @@
 <li class="toctree-l1"><a class="reference internal" href="insts.html">Built-in quantum instructions</a><ul>
 <li class="toctree-l2"><a class="reference internal" href="insts.html#initialization">Initialization</a></li>
 <li class="toctree-l2"><a class="reference internal" href="insts.html#measurement">Measurement</a></li>
+<li class="toctree-l2"><a class="reference internal" href="insts.html#explicit-no-operation">Explicit no-operation</a></li>
 </ul>
 </li>
 <li class="toctree-l1"><a class="reference internal" href="classical.html">Classical instructions</a><ul>

language/index.html

@@ -36,7 +36,7 @@
 
   <section id="built-in-quantum-instructions">
 <h1>Built-in quantum instructions<a class="headerlink" href="#built-in-quantum-instructions" title="Link to this heading">¶</a></h1>
-<p>This section describes built-in non-unitary operations.</p>
+<p>This section describes built-in operations on qubits, including non-unitary ones.</p>
 <section id="initialization">
 <h2>Initialization<a class="headerlink" href="#initialization" title="Link to this heading">¶</a></h2>
 <p>The statement <code class="docutils literal notranslate"><span class="pre">reset</span> <span class="pre">qubit|qubit[];</span></code> resets a qubit or quantum register to the state
@@ -105,6 +105,42 @@ <h2>Measurement<a class="headerlink" href="#measurement" title="Link to this hea
 </figcaption>
 </figure>
 </section>
+<section id="explicit-no-operation">
+<span id="nop"></span><h2>Explicit no-operation<a class="headerlink" href="#explicit-no-operation" title="Link to this heading">¶</a></h2>
+<div class="versionadded">
+<p><span class="versionmodified added">Added in version 3.2: </span>The entire <code class="docutils literal notranslate"><span class="pre">nop</span></code> directive.</p>
+</div>
+<p>The statement <code class="docutils literal notranslate"><span class="pre">nop</span> <span class="pre">&lt;qubits&gt;;</span></code> is an explicit no-operation on all mentioned qubits, but marks them as being “used” within a scope.
+<code class="docutils literal notranslate"><span class="pre">&lt;qubits&gt;</span></code> is a comma-separated list of qubit or qubit-register operands.</p>
+<p>In the global scope this has no effect on the program operation, though a compiler must still validate the arguments.
+This has a particularly important effect on <span class="xref std std-ref">boxed scopes</span>; a <code class="docutils literal notranslate"><span class="pre">nop</span></code> counts as a “use” of the qubit within the <code class="docutils literal notranslate"><span class="pre">box</span></code>, causing the qubit to be synchronized with the rest of the box at entry and exit.</p>
+<p>A <code class="docutils literal notranslate"><span class="pre">nop</span></code> statement is valid in exactly the places that a gate-call statement is valid.
+The operands of a <code class="docutils literal notranslate"><span class="pre">nop</span></code> statement must all be in scope and be of type <code class="docutils literal notranslate"><span class="pre">qubit</span></code> or <code class="docutils literal notranslate"><span class="pre">qubit[n]</span></code> for any non-negative integer <code class="docutils literal notranslate"><span class="pre">n</span></code>.</p>
+<p>For example:</p>
+<div class="highlight-qasm3 notranslate"><div class="highlight"><pre><span></span><span class="kn">include</span><span class="w"> </span><span class="s">&quot;stdgates.inc&quot;</span><span class="p">;</span>
+
+<span class="kt">stretch</span><span class="w"> </span><span class="n">s</span><span class="p">;</span>
+<span class="k">box</span><span class="w"> </span><span class="p">[</span><span class="n">s</span><span class="p">]</span><span class="w"> </span><span class="p">{</span>
+<span class="w">   </span><span class="c1">// Qubits $0 and $1 are explicitly used by the `cx`.</span>
+<span class="w">   </span><span class="n">cx</span><span class="w"> </span><span class="l">$0</span><span class="p">,</span><span class="w"> </span><span class="l">$1</span><span class="p">;</span>
+
+<span class="w">   </span><span class="c1">// Qubit $2 must be synchronized to $0 and $1 at the start</span>
+<span class="w">   </span><span class="c1">// and end of the box, but has no defined operations within</span>
+<span class="w">   </span><span class="c1">// the box.</span>
+<span class="w">   </span><span class="n">nop</span><span class="w"> </span><span class="l">$2</span><span class="p">;</span>
+
+<span class="w">   </span><span class="c1">// More than one qubit can be specified in the list.  It is</span>
+<span class="w">   </span><span class="c1">// not an error to duplicate qubits, nor to ``nop`` a qubit</span>
+<span class="w">   </span><span class="c1">// with explicit operations in this scope.</span>
+<span class="w">   </span><span class="n">nop</span><span class="w"> </span><span class="l">$3</span><span class="p">,</span><span class="w"> </span><span class="l">$0</span><span class="p">;</span>
+
+<span class="w">   </span><span class="c1">// The ``nop`` statement can have zero operands, and this</span>
+<span class="w">   </span><span class="c1">// has no observable effect at all.</span>
+<span class="w">   </span><span class="n">nop</span><span class="p">;</span>
+<span class="p">}</span>
+</pre></div>
+</div>
+</section>
 </section>
 
 
@@ -135,6 +171,7 @@ <h3>Navigation</h3>
 <li class="toctree-l2 current"><a class="current reference internal" href="#">Built-in quantum instructions</a><ul>
 <li class="toctree-l3"><a class="reference internal" href="#initialization">Initialization</a></li>
 <li class="toctree-l3"><a class="reference internal" href="#measurement">Measurement</a></li>
+<li class="toctree-l3"><a class="reference internal" href="#explicit-no-operation">Explicit no-operation</a></li>
 </ul>
 </li>
 <li class="toctree-l2"><a class="reference internal" href="classical.html">Classical instructions</a></li>

language/insts.html

@@ -34,10 +34,10 @@
 
   <section id="release-notes">
 <h1>Release Notes<a class="headerlink" href="#release-notes" title="Link to this heading">¶</a></h1>
-<section id="spec-v3-1-0-32">
-<span id="release-notes-spec-v3-1-0-32"></span><h2>spec/v3.1.0-32<a class="headerlink" href="#spec-v3-1-0-32" title="Link to this heading">¶</a></h2>
+<section id="spec-v3-1-0-33">
+<span id="release-notes-spec-v3-1-0-33"></span><h2>spec/v3.1.0-33<a class="headerlink" href="#spec-v3-1-0-33" title="Link to this heading">¶</a></h2>
 <section id="new-features">
-<span id="release-notes-spec-v3-1-0-32-new-features"></span><h3>New Features<a class="headerlink" href="#new-features" title="Link to this heading">¶</a></h3>
+<span id="release-notes-spec-v3-1-0-33-new-features"></span><h3>New Features<a class="headerlink" href="#new-features" title="Link to this heading">¶</a></h3>
 <ul class="simple">
 <li><p>The types <code class="docutils literal notranslate"><span class="pre">bool</span></code> and (scalar) <code class="docutils literal notranslate"><span class="pre">bit</span></code> are now explicitly described as being completely
 interchangeable in expression (r-value) positions, and that <code class="docutils literal notranslate"><span class="pre">bit</span></code> and <code class="docutils literal notranslate"><span class="pre">bit[1]</span></code> are distinct
@@ -54,9 +54,14 @@ <h1>Release Notes<a class="headerlink" href="#release-notes" title="Link to this
 To support namespaced annotations, the annotations keyword may now include
 a dotted (‘.’) list of identifiers.</p></li>
 </ul>
+<ul class="simple">
+<li><p>Added an explicit no-operation statement <code class="docutils literal notranslate"><span class="pre">nop</span> <span class="pre">&lt;qubits&gt;;</span></code>, which can be used to mark qubits as
+“used” by a scope (such as a <code class="docutils literal notranslate"><span class="pre">box</span></code>) without implying any operations on them.  See <a class="reference internal" href="language/insts.html#nop"><span class="std std-ref">Explicit no-operation</span></a>
+for full details.</p></li>
+</ul>
 </section>
 <section id="upgrade-notes">
-<span id="release-notes-spec-v3-1-0-32-upgrade-notes"></span><h3>Upgrade Notes<a class="headerlink" href="#upgrade-notes" title="Link to this heading">¶</a></h3>
+<span id="release-notes-spec-v3-1-0-33-upgrade-notes"></span><h3>Upgrade Notes<a class="headerlink" href="#upgrade-notes" title="Link to this heading">¶</a></h3>
 <ul class="simple">
 <li><p>It has been clarified that arrays and registers of size zero are
 allowed; however, integers and angles must have size greater than
@@ -70,7 +75,7 @@ <h1>Release Notes<a class="headerlink" href="#release-notes" title="Link to this
 </ul>
 </section>
 <section id="bug-fixes">
-<span id="release-notes-spec-v3-1-0-32-bug-fixes"></span><h3>Bug Fixes<a class="headerlink" href="#bug-fixes" title="Link to this heading">¶</a></h3>
+<span id="release-notes-spec-v3-1-0-33-bug-fixes"></span><h3>Bug Fixes<a class="headerlink" href="#bug-fixes" title="Link to this heading">¶</a></h3>
 <ul class="simple">
 <li><p>Clarify that array type variables are supported as inputs.</p></li>
 </ul>
@@ -106,7 +111,7 @@ <h3>Navigation</h3>
 <li class="toctree-l1"><a class="reference internal" href="language/index.html">Language</a></li>
 <li class="toctree-l1"><a class="reference internal" href="grammar/index.html">OpenQASM 3.0 Grammar</a></li>
 <li class="toctree-l1 current"><a class="current reference internal" href="#">Release Notes</a><ul>
-<li class="toctree-l2"><a class="reference internal" href="#spec-v3-1-0-32">spec/v3.1.0-32</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="#spec-v3-1-0-33">spec/v3.1.0-33</a><ul>
 <li class="toctree-l3"><a class="reference internal" href="#new-features">New Features</a></li>
 <li class="toctree-l3"><a class="reference internal" href="#upgrade-notes">Upgrade Notes</a></li>
 <li class="toctree-l3"><a class="reference internal" href="#bug-fixes">Bug Fixes</a></li>