Merge pull request #279 from kevinsung/xxyy

Add XXPLUSYY and XXMINUSYY gates

Author: jcmgray

docs/tensor-circuit.ipynb

@@ -845,6 +845,68 @@ def givens2_param_gen(params):
 register_param_gate("GIVENS2", givens2_param_gen, num_qubits=2)
 
 
+def xx_plus_yy_param_gen(params):
+    theta, beta = params[0], params[1]
+
+    with backend_like(theta):
+        # get a real backend zero
+        zero = 0.0 * theta
+        half_theta = 0.5 * theta
+
+        a = do("complex", do("cos", half_theta), zero)
+        b = do("exp", do("complex", zero, beta)) * do(
+            "complex", do("sin", half_theta), zero
+        )
+        b_conj = do("exp", do("complex", zero, -beta)) * do(
+            "complex", do("sin", half_theta), zero
+        )
+
+        # get a complex backend zero and backend one
+        zero = do("complex", zero, zero)
+        one = zero + 1.0
+
+        data = (
+            (((one, zero), (zero, zero)), ((zero, a), (-1j * b, zero))),
+            (((zero, -1j * b_conj), (a, zero)), ((zero, zero), (zero, one))),
+        )
+
+        return recursive_stack(data)
+
+
+register_param_gate("XXPLUSYY", xx_plus_yy_param_gen, num_qubits=2)
+
+
+def xx_minus_yy_param_gen(params):
+    theta, beta = params[0], params[1]
+
+    with backend_like(theta):
+        # get a real backend zero
+        zero = 0.0 * theta
+        half_theta = 0.5 * theta
+
+        a = do("complex", do("cos", half_theta), zero)
+        b = do("exp", do("complex", zero, beta)) * do(
+            "complex", do("sin", half_theta), zero
+        )
+        b_conj = do("exp", do("complex", zero, -beta)) * do(
+            "complex", do("sin", half_theta), zero
+        )
+
+        # get a complex backend zero and backend one
+        zero = do("complex", zero, zero)
+        one = zero + 1.0
+
+        data = (
+            (((a, zero), (zero, -1j * b_conj)), ((zero, one), (zero, zero))),
+            (((zero, zero), (one, zero)), ((-1j * b, zero), (zero, a))),
+        )
+
+        return recursive_stack(data)
+
+
+register_param_gate("XXMINUSYY", xx_minus_yy_param_gen, num_qubits=2)
+
+
 def rxx_param_gen(params):
     r"""Parametrized two qubit XX-rotation.
 
@@ -2300,6 +2362,34 @@ def givens2(
             **kwargs,
         )
 
+    def xx_plus_yy(
+        self, theta, beta, i, j, gate_round=None, parametrize=False, **kwargs
+    ):
+        self.apply_gate(
+            "XXPLUSYY",
+            theta,
+            beta,
+            i,
+            j,
+            gate_round=gate_round,
+            parametrize=parametrize,
+            **kwargs,
+        )
+
+    def xx_minus_yy(
+        self, theta, beta, i, j, gate_round=None, parametrize=False, **kwargs
+    ):
+        self.apply_gate(
+            "XXMINUSYY",
+            theta,
+            beta,
+            i,
+            j,
+            gate_round=gate_round,
+            parametrize=parametrize,
+            **kwargs,
+        )
+
     def rxx(self, theta, i, j, gate_round=None, parametrize=False, **kwargs):
         self.apply_gate(
             "RXX",

quimb/tensor/circuit.py

@@ -277,6 +277,8 @@ def test_all_gate_methods(self, Circ):
             ("fsimg", 2, 5),
             ("givens", 2, 1),
             ("givens2", 2, 2),
+            ("xx_plus_yy", 2, 2),
+            ("xx_minus_yy", 2, 2),
             ("su4", 2, 15),
         ]
         random.shuffle(g_nq_np)

tests/test_tensor/test_circuit.py

@@ -249,6 +249,8 @@ def test_every_parametrized_gate(backend):
     circ.fsimg(*qu.randn(5), 1, 0, parametrize=True, tags=["OPTIMIZE"])
     circ.givens(*qu.randn(1), 0, 1, parametrize=True, tags=["OPTIMIZE"])
     circ.givens2(*qu.randn(2), 0, 1, parametrize=True, tags=["OPTIMIZE"])
+    circ.xx_plus_yy(*qu.randn(2), 0, 1, parametrize=True, tags=["OPTIMIZE"])
+    circ.xx_minus_yy(*qu.randn(2), 0, 1, parametrize=True, tags=["OPTIMIZE"])
     circ.su4(*qu.randn(15), 0, 1, parametrize=True, tags=["OPTIMIZE"])
     psi = circ.psi