diff --git a/src/circuit_json.rs b/src/circuit_json.rs
index c4d34b2..d442abc 100644
--- a/src/circuit_json.rs
+++ b/src/circuit_json.rs
@@ -206,6 +206,7 @@ pub struct ImplicitPermutation(pub Register, pub Register);
 
 /// Pytket canonical serialized circuit
 #[derive(Deserialize, Serialize, Clone, Debug, PartialEq)]
+#[non_exhaustive]
 pub struct SerialCircuit<P = String> {
     /// The name of the circuit.
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -223,6 +224,12 @@ pub struct SerialCircuit<P = String> {
     /// Number of wasm wires in the circuit.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub number_of_ws: Option<u64>,
+    /// A list of qubits initialized at the start of the circuit.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub created_qubits: Option<Vec<Register>>,
+    /// A list of qubits discarded at the end of the circuit.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub discarded_qubits: Option<Vec<Register>>,
 }
 
 impl<P> Default for Operation<P> {
@@ -241,6 +248,22 @@ impl<P> Default for Operation<P> {
     }
 }
 
+impl<P: Default> Default for SerialCircuit<P> {
+    fn default() -> Self {
+        Self {
+            name: None,
+            phase: Default::default(),
+            commands: Default::default(),
+            qubits: Default::default(),
+            bits: Default::default(),
+            implicit_permutation: Default::default(),
+            number_of_ws: None,
+            created_qubits: None,
+            discarded_qubits: None,
+        }
+    }
+}
+
 impl<P> Operation<P> {
     /// Returns a default-initialized Operation with the given type.
     ///
@@ -289,6 +312,21 @@ impl<P> Command<P> {
 }
 
 impl<P> SerialCircuit<P> {
+    /// Initialize a new SerialCircuit with the given name and phase.
+    pub fn new(name: Option<String>, phase: P) -> Self {
+        Self {
+            name,
+            phase,
+            commands: Vec::new(),
+            qubits: Vec::new(),
+            bits: Vec::new(),
+            implicit_permutation: Vec::new(),
+            number_of_ws: None,
+            created_qubits: None,
+            discarded_qubits: None,
+        }
+    }
+
     /// Applies a function over the parameters of the circuit.
     ///
     /// Returns a new SerialCircuit with the same data, but with a new generic
@@ -308,6 +346,8 @@ impl<P> SerialCircuit<P> {
             bits: self.bits,
             implicit_permutation: self.implicit_permutation,
             number_of_ws: self.number_of_ws,
+            created_qubits: self.created_qubits,
+            discarded_qubits: self.discarded_qubits,
         }
     }
 }