We propose an integrated front-end data acquisition circuit for a hybrid ultrasound (US)-gamma probe. The proposed circuit consists of three main parts: (1) a preamplifier for the gamma probe, (2) a preprocessing analog circuit for the US, and (3) a digitally controlled analog switch. By exploiting the long idle time of the US system, an analog switch can be used to acquire data of both systems using a single output channel simultaneously. On the nuclear medicine (NM) gamma probe side, energy resolutions of 18.4% and 17.5% were acquired with the standalone system and with the proposed switching circuit, respectively, when irradiated with a Co-57 radiation source. Similarly, signal-to-noise ratios of 14.89 and 13.12 dB were achieved when US echo signals were acquired with the standalone system and with the proposed switching circuit, respectively. Lastly, a combined US-gamma probe was used to scan a glass target and a sealed radiation source placed in a water tank. The results confirmed that, by using a hybrid US-gamma probe system, it is possible to distinguish between the two objects and acquire structural information (ultrasound) alongside molecular information (gamma radiation source).

A private quantum channel (PQC) in quantum cryptography is one of the most well-known quantum cryptographic protocols using a secret key obtained from the quantum key distribution (QKD) protocol, and it is called a quantum one-time pad or random unitary channel and so on. The reason a PQC is important is that the output state of the channel always gives rise to a maximally mixed state, so the quantum communication can be secured without any external eavesdropping; thus, it preserves information-theoretic security. We explicitly construct five kinds of single-qubit PQCs and try to connect each to a 3-dimensional polyhedron. We expand a corresponding method between four unitary matrices given by Pauli matrices and the regular tetrahedron, and find specific unitary matrices corresponding to another four regular polyhedra. Each unitary matrix is naturally connected to a pre-shared key obtained by using the QKD protocol, which completes a model of five kinds of PQCs for the single-qubit state. Finally, we analyze a trade-off relation between security and efficiency for the PQC.

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