Documentation for NVQC (#1412)

.github/workflows/config/md_link_check_config.json

@@ -23,6 +23,12 @@
       },
       {
         "pattern": "openapi.html"
+      },
+      {
+        "pattern": "^https://www.nvidia.com/en-us/solutions/quantum-computing/cloud"
+      },
+      {
+        "pattern": "^https://developer.nvidia.com/quantum-cloud-early-access"
       }
     ]
-}
+}

.github/workflows/config/spelling_allowlist.txt

@@ -220,6 +220,7 @@ reStructuredText
 runtime
 rvalue
 scalability
+scalable
 sexualized
 struct
 structs

.github/workflows/python_wheels.yml

@@ -289,7 +289,7 @@ jobs:
           docker run --rm -dit --name wheel-validation-snippets wheel_validation:local
           status_sum=0
 
-          for ex in `find docs/sphinx/snippets/python -name '*.py' -not -path '*/platform/*'`; do
+          for ex in `find docs/sphinx/snippets/python -name '*.py' -not -path '*/platform/*' -not -path '*/nvqc/*'`; do
             file="${ex#docs/sphinx/snippets/python/}"
             echo "__Snippet ${file}:__" >> /tmp/validation.out
             (docker exec wheel-validation-snippets bash -c "python${{ inputs.python_version }} /tmp/snippets/$file" >> /tmp/validation.out) && success=true || success=false

docs/sphinx/releases.rst

@@ -12,7 +12,12 @@ The latest version of CUDA Quantum is on the main branch of our `GitHub reposito
 
 **0.7.0**
 
-The 0.7.0 release adds support for using NVIDIA Quantum Cloud, giving you access to our most powerful GPU-accelerated simulators even if you don't have an NVIDIA GPU. With 0.7.0, we have furthermore greatly increased expressiveness of the Python and C++ language frontends. Check our our `documentation <https://nvidia.github.io/cuda-quantum/latest/using/quick_start.html>`__ to learn more about the new Python syntax support we have added, and `follow our blog <https://developer.nvidia.com/cuda-q>`__ to learn more about the new setup and its performance benefits.
+The 0.7.0 release adds support for using :doc:`NVIDIA Quantum Cloud <using/backends/nvqc>`,
+giving you access to our most powerful GPU-accelerated simulators even if you don't have an NVIDIA GPU.
+With 0.7.0, we have furthermore greatly increased expressiveness of the Python and C++ language frontends. 
+Check out our `documentation <https://nvidia.github.io/cuda-quantum/latest/using/quick_start.html>`__ 
+to get started with the new Python syntax support we have added, and `follow our blog <https://developer.nvidia.com/cuda-q>`__
+to learn more about the new setup and its performance benefits.
 
 - `Docker image <https://catalog.ngc.nvidia.com/orgs/nvidia/containers/cuda-quantum>`__
 - `Python wheel <https://pypi.org/project/cuda-quantum/>`__

docs/sphinx/snippets/cpp/using/cudaq/nvqc/nvqc_intro.cpp

@@ -0,0 +1,29 @@
+/*******************************************************************************
+ * Copyright (c) 2022 - 2024 NVIDIA Corporation & Affiliates.                  *
+ * All rights reserved.                                                        *
+ *                                                                             *
+ * This source code and the accompanying materials are made available under    *
+ * the terms of the Apache License 2.0 which accompanies this distribution.    *
+ ******************************************************************************/
+
+// [Begin Documentation]
+#include <cudaq.h>
+
+// Define a simple quantum kernel to execute on NVQC.
+struct ghz {
+  // Maximally entangled state between 25 qubits.
+  auto operator()() __qpu__ {
+    constexpr int NUM_QUBITS = 25;
+    cudaq::qvector q(NUM_QUBITS);
+    h(q[0]);
+    for (int i = 0; i < NUM_QUBITS - 1; i++) {
+      x<cudaq::ctrl>(q[i], q[i + 1]);
+    }
+    auto result = mz(q);
+  }
+};
+
+int main() {
+  auto counts = cudaq::sample(ghz{});
+  counts.dump();
+}

docs/sphinx/snippets/cpp/using/cudaq/nvqc/nvqc_mqpu.cpp

@@ -0,0 +1,51 @@
+/*******************************************************************************
+ * Copyright (c) 2022 - 2024 NVIDIA Corporation & Affiliates.                  *
+ * All rights reserved.                                                        *
+ *                                                                             *
+ * This source code and the accompanying materials are made available under    *
+ * the terms of the Apache License 2.0 which accompanies this distribution.    *
+ ******************************************************************************/
+
+// [Begin Documentation]
+#include <cudaq.h>
+#include <cudaq/algorithm.h>
+#include <cudaq/gradients.h>
+#include <cudaq/optimizers.h>
+#include <iostream>
+
+int main() {
+  using namespace cudaq::spin;
+  cudaq::spin_op h = 5.907 - 2.1433 * x(0) * x(1) - 2.1433 * y(0) * y(1) +
+                     .21829 * z(0) - 6.125 * z(1);
+
+  auto [ansatz, theta] = cudaq::make_kernel<double>();
+  auto q = ansatz.qalloc();
+  auto r = ansatz.qalloc();
+  ansatz.x(q);
+  ansatz.ry(theta, r);
+  ansatz.x<cudaq::ctrl>(r, q);
+
+  // Run VQE with a gradient-based optimizer.
+  // Delegate cost function and gradient computation across different NVQC-based
+  // QPUs.
+  // Note: this needs to be compiled with `--nvqc-nqpus 3` create 3 virtual
+  // QPUs.
+  cudaq::optimizers::lbfgs optimizer;
+  auto [opt_val, opt_params] = optimizer.optimize(
+      /*dim=*/1, /*opt_function*/ [&](const std::vector<double> &params,
+                                      std::vector<double> &grads) {
+        // Queue asynchronous jobs to do energy evaluations across multiple QPUs
+        auto energy_future =
+            cudaq::observe_async(/*qpu_id=*/0, ansatz, h, params[0]);
+        const double paramShift = M_PI_2;
+        auto plus_future = cudaq::observe_async(/*qpu_id=*/1, ansatz, h,
+                                                params[0] + paramShift);
+        auto minus_future = cudaq::observe_async(/*qpu_id=*/2, ansatz, h,
+                                                 params[0] - paramShift);
+        grads[0] = (plus_future.get().expectation() -
+                    minus_future.get().expectation()) /
+                   2.0;
+        return energy_future.get().expectation();
+      });
+  std::cout << "Minimum energy = " << opt_val << " (expected -1.74886).\n";
+}

docs/sphinx/snippets/python/using/cudaq/nvqc/nvqc_intro.py

@@ -0,0 +1,23 @@
+# ============================================================================ #
+# Copyright (c) 2022 - 2024 NVIDIA Corporation & Affiliates.                   #
+# All rights reserved.                                                         #
+#                                                                              #
+# This source code and the accompanying materials are made available under     #
+# the terms of the Apache License 2.0 which accompanies this distribution.     #
+# ============================================================================ #
+# [Begin Documentation]
+import cudaq
+
+cudaq.set_target("nvqc")
+num_qubits = 25
+# Define a simple quantum kernel to execute on NVQC.
+kernel = cudaq.make_kernel()
+qubits = kernel.qalloc(num_qubits)
+# Maximally entangled state between 25 qubits.
+kernel.h(qubits[0])
+for i in range(num_qubits - 1):
+    kernel.cx(qubits[i], qubits[i + 1])
+kernel.mz(qubits)
+
+counts = cudaq.sample(kernel)
+print(counts)

docs/sphinx/snippets/python/using/cudaq/nvqc/nvqc_mqpu.py

@@ -0,0 +1,54 @@
+# ============================================================================ #
+# Copyright (c) 2022 - 2024 NVIDIA Corporation & Affiliates.                   #
+# All rights reserved.                                                         #
+#                                                                              #
+# This source code and the accompanying materials are made available under     #
+# the terms of the Apache License 2.0 which accompanies this distribution.     #
+# ============================================================================ #
+# [Begin Documentation]
+import cudaq
+from cudaq import spin
+import math
+
+# Use NVQC with 3 virtual QPUs
+cudaq.set_target("nvqc", nqpus=3)
+
+print("Number of QPUs:", cudaq.get_target().num_qpus())
+# Create the parameterized ansatz
+kernel, theta = cudaq.make_kernel(float)
+qreg = kernel.qalloc(2)
+kernel.x(qreg[0])
+kernel.ry(theta, qreg[1])
+kernel.cx(qreg[1], qreg[0])
+
+# Define its spin Hamiltonian.
+hamiltonian = (5.907 - 2.1433 * spin.x(0) * spin.x(1) -
+               2.1433 * spin.y(0) * spin.y(1) + 0.21829 * spin.z(0) -
+               6.125 * spin.z(1))
+
+
+def opt_gradient(parameter_vector):
+    # Evaluate energy and gradient on different remote QPUs
+    # (i.e., concurrent job submissions to NVQC)
+    energy_future = cudaq.observe_async(kernel,
+                                        hamiltonian,
+                                        parameter_vector[0],
+                                        qpu_id=0)
+    plus_future = cudaq.observe_async(kernel,
+                                      hamiltonian,
+                                      parameter_vector[0] + 0.5 * math.pi,
+                                      qpu_id=1)
+    minus_future = cudaq.observe_async(kernel,
+                                       hamiltonian,
+                                       parameter_vector[0] - 0.5 * math.pi,
+                                       qpu_id=2)
+    return (energy_future.get().expectation(), [
+        (plus_future.get().expectation() - minus_future.get().expectation()) /
+        2.0
+    ])
+
+
+optimizer = cudaq.optimizers.LBFGS()
+optimal_value, optimal_parameters = optimizer.optimize(1, opt_gradient)
+print("Ground state energy =", optimal_value)
+print("Optimal parameters =", optimal_parameters)

docs/sphinx/using/backends/backends.rst

@@ -7,6 +7,7 @@ CUDA Quantum Backends
 
       Simulation <simulators.rst>
       Quantum Hardware <hardware.rst>
+      NVIDIA Quantum Cloud <nvqc.rst>
       Multi-Processor Platforms <platform.rst>
 
 **The following is a comprehensive list of the available targets in CUDA Quantum:**
@@ -18,6 +19,7 @@ CUDA Quantum Backends
 * :ref:`nvidia-fp64 <nvidia-fp64-backend>`
 * :ref:`nvidia-mqpu <nvidia-mgpu-backend>`
 * :ref:`nvidia-mqpu-fp64 <nvidia-mgpu-backend>`
+* :doc:`nvqc <nvqc>`
 * :ref:`oqc <oqc-backend>`
 * :ref:`qpp-cpu <qpp-cpu-backend>`
 * :ref:`quantinuum <quantinuum-backend>`