Secure Multiparty Delegated Quantum Computation: Difference between revisions

==Pseudo Code==

*Enforcing honest behavior for client </math>C_k</math>

# Client </math>C_k</math> sends </math>m</math> qubits </math>\ket{+_{\theta_i^k}}=\frac{1}{\sqrt{2}}(\ket{0}+e^{i\theta_i^k}\ket{1})</math> to the Server and secret-shares the values </math>\{\theta_i^k\}_{i=1}^m</math> with all clients, using a VSS scheme.

# The Server requests the shared values from the clients for all but one qubit, and measures in the resconstructed bases. If the bases agree with the results of the measurements, then with high probability, the remaining state is correctly formed in relation to the shared angle.

*State preparation for </math>j\in I</math>)

#Server stores states received from clients </math>C_k</math> to distinct registers </math>\mathcal{S}_k\subset \mathcal{S}</math> (</math>k=1,\dots,n</math>);

##for </math>k=1,\dots,n-1</math>

###if </math>k=j</math> '''then''' break;

###if </math>k=n-1</math> and </math>j=n</math> '''then''' break;

###if </math>k=j-1</math>, '''then'''

####CNOT on </math>\mathcal{S}_k\otimes\mathcal{S}_{k+2}</math>;

###'''else'''

####CNOT on </math>\mathcal{S}_k\otimes\mathcal{S}_{k+1}</math>;

###measure state in </math>\mathcal{S}_k</math> and get outcome </math>t_j^k</math>;

##if </math>j=n</math> '''then'''

###CNOT on </math>\mathcal{S}_{n-1}\otimes\mathcal{S}_n</math>;

####measure state in </math>\mathcal{S}_{n-1}</math> and get outcome </math>t_n^{n-1}</math>;

###else

####CNOT on </math>(\mathcal{S}_{n}\otimes\mathcal{S}_j)</math>;