Remove parsing catalyst device attribute dictionary for shots (#1017)

**Context:**
As part of the work to support dynamic measurement shapes,
PennyLaneAI/catalyst#1310 in Catalyst is
allowing a quantum device to take in a dynamic number of shots at the
mlir level. One of the changes involved is that the `DeviceInitOp` now
takes in a proper SSA argument for shots, instead of having shots as
just another entry in the `DeviceInitOp`'s attribute dictionary.

Correspondingly, the backend devices' catalyst interfaces need to stop
parsing the `DeviceInitOp`'s attribute dictionary for shots.

**Description of the Change:**
The backend devices' catalyst interfaces stop parsing the
`DeviceInitOp`'s attribute dictionary for shots.

**Benefits:**
Agreement with Catalyst on how device shots, potentially dynamic, is
handled.

**Possible Drawbacks:**

**Related GitHub Issues:**

---------

Co-authored-by: ringo-but-quantum <[email protected]>

Author: 2 people

.github/CHANGELOG.md

@@ -26,6 +26,9 @@
 
 ### Improvements
 
+* Catalyst device interfaces support dynamic shots, and no longer parses the device init op's attribute dictionary for a static shots literal.
+  [(#1017)](https://github.com/PennyLaneAI/pennylane-lightning/pull/1017)
+
 * Reduce flaky test and increase test shots count.
   [(#1015)](https://github.com/PennyLaneAI/pennylane-lightning/pull/1015)
 

pennylane_lightning/core/src/simulators/lightning_gpu/catalyst/LightningGPUSimulator.hpp

@@ -61,7 +61,7 @@ class LightningGPUSimulator final : public Catalyst::Runtime::QuantumDevice {
     Catalyst::Runtime::CacheManager<std::complex<double>> cache_manager{};
     bool tape_recording{false};
 
-    std::size_t device_shots;
+    std::size_t device_shots{0};
 
     std::mt19937 *gen{nullptr};
 
@@ -108,9 +108,6 @@ class LightningGPUSimulator final : public Catalyst::Runtime::QuantumDevice {
   public:
     explicit LightningGPUSimulator(const std::string &kwargs = "{}") {
         auto &&args = Catalyst::Runtime::parse_kwargs(kwargs);
-        device_shots = args.contains("shots")
-                           ? static_cast<std::size_t>(std::stoll(args["shots"]))
-                           : 0;
     }
     ~LightningGPUSimulator() = default;
 

pennylane_lightning/core/src/simulators/lightning_kokkos/catalyst/LightningKokkosSimulator.hpp

@@ -109,9 +109,6 @@ class LightningKokkosSimulator final : public Catalyst::Runtime::QuantumDevice {
     explicit LightningKokkosSimulator(
         const std::string &kwargs = "{}") noexcept {
         auto &&args = Catalyst::Runtime::parse_kwargs(kwargs);
-        device_shots = args.contains("shots")
-                           ? static_cast<std::size_t>(std::stoll(args["shots"]))
-                           : 0;
     }
     ~LightningKokkosSimulator() noexcept = default;
 

pennylane_lightning/core/src/simulators/lightning_qubit/catalyst/LightningSimulator.hpp

@@ -50,7 +50,7 @@ class LightningSimulator final : public Catalyst::Runtime::QuantumDevice {
     Catalyst::Runtime::QubitManager<QubitIdType, size_t> qubit_manager{};
     Catalyst::Runtime::CacheManager<std::complex<double>> cache_manager{};
     bool tape_recording{false};
-    size_t device_shots;
+    size_t device_shots{0};
 
     std::mt19937 *gen = nullptr;
 
@@ -101,9 +101,6 @@ class LightningSimulator final : public Catalyst::Runtime::QuantumDevice {
         const std::string &kwargs = "{}") // NOLINT(hicpp-member-init)
     {
         auto &&args = Catalyst::Runtime::parse_kwargs(kwargs);
-        device_shots = args.contains("shots")
-                           ? static_cast<size_t>(std::stoll(args["shots"]))
-                           : 0;
         mcmc = args.contains("mcmc") ? args["mcmc"] == "True" : false;
         num_burnin = args.contains("num_burnin")
                          ? static_cast<size_t>(std::stoll(args["num_burnin"]))

pennylane_lightning/core/src/simulators/lightning_qubit/catalyst/tests/Test_LightningDriver.cpp

@@ -26,9 +26,9 @@ TEST_CASE("Test parse_kwargs coverage", "[Utils]") {
     std::string case1;
     CHECK(parse_kwargs(case1).empty());
 
-    std::string case2{"{shots : 1000}"};
-    std::string case3{"shots : 1000"};
-    std::string case4{"'shots':'1000'"};
+    std::string case2{"{my_attr : 1000}"};
+    std::string case3{"my_attr : 1000"};
+    std::string case4{"'my_attr':'1000'"};
     CHECK(parse_kwargs(case2) == parse_kwargs(case3));
     CHECK(parse_kwargs(case3) == parse_kwargs(case4));
 
@@ -40,13 +40,12 @@ TEST_CASE("Test parse_kwargs coverage", "[Utils]") {
     CHECK((res5.contains("E") && res5["E"] == "F"));
 
     std::string case6{
-        "device_type : braket.aws.qubit,{'shots': 0, 'device_arn': 'sv1', "
+        "device_type : braket.aws.qubit,{'device_arn': 'sv1', "
         "'s3_destination_folder': \"('catalyst-op3-s3', 'prefix')\"}"};
     auto res6 = parse_kwargs(case6);
-    CHECK(res6.size() == 4);
+    CHECK(res6.size() == 3);
     CHECK((res6.contains("device_type") &&
            res6["device_type"] == "braket.aws.qubit"));
-    CHECK((res6.contains("shots") && res6["shots"] == "0"));
     CHECK((res6.contains("device_arn") && res6["device_arn"] == "sv1"));
     CHECK((res6.contains("s3_destination_folder") &&
            res6["s3_destination_folder"] == "('catalyst-op3-s3', 'prefix')"));